(navigation image)
Home American Libraries | Canadian Libraries | Universal Library | Community Texts | Project Gutenberg | Children's Library | Biodiversity Heritage Library | Additional Collections
Search: Advanced Search
Anonymous User (login or join us)
Upload
See other formats

Full text of "Zoology (Std12 - English Medium)"

ZOOLOGY 



HIGHER SECONDARY - SECOND YEAR 



Untouchability is a sin 
Untouchability is a crime 
Untouchability is inhuman 



<s$$* 




'■"-i 



TAMIL NADU 

TEXTBOOK CORPORATION 

College Road, Chennai - 600 006. 



© Government of Tamilnadu 
First Edition - 2005 
Reprint - 2006 

Chairperson 

Prof. T. SARGUNAM STEPHEN 

P. G and Research Dept. of Zoology 

Govt. Arts College 

Nandanam, Chennai - 600 035. 

Reviewers 
Dr. K. Vijayaraman Dr. K. Ramalingam 

Reader Head, P. G. Dept. of Zoology Reader RG and Research Dept. of Zoology 
Periyar EVR Govt. Arts College Govt. Arts College, Nandanam, 

Trichy - 620 020. Chennai- 600 035. 

Dr. P. Daisy 

Reader and Head, Dept. of 

Zoology and Biotechnology 

Holy Cross College 

Trichy - 620 002. 

Authors 

Tmt. Kannaki Prabakaran Dr. (Tmt) Flankit Thomas 

PGT. in Zoology PGT in Zoology 

Sri R.K.M.SaradaVidyala Model CSI Jessie Moses Mat. and Hr.Sec School 

Hr. Sec. School, T.Nagar, Chennai - 17. Anna nagar, Chennai - 600 040. 

Thiru. T. Sekar Thiru N. Kumaravel 

PGT. in Zoology PGT in Zoology 

Govt.Girls Higher Sec School M.F.S.D. Higher Sec.School 

Choolaimedu, Chennai - 600 094. Sowcarpet, Chennai - 600 079. 

Price : Rs. 



This book has been prepared by The Directorate of School 
Education on behalf of the Government of Tamilnadu. 



This book has been printed on 60 GSM Paper. 



Preface 

Biology or Life science has made rapid progress. Advancements in 
several fields of Science and Technology have provided the tools to 
understand life processes. As humanity faces several problems related to 
population growth, environmental degradation, energy crisis, epidemic 
diseases, food production and species extinctions the challenges faced by 
the biologists in finding appropriate solutions to such issues has become his/ 
her sacred duty. Thus the future remedial measures for ensuring human sur- 
vival and biosphere safeguarding shall require a vast army of personnel with 
a sound knowledge of Biology. Hence the scope for future biologists is 
evergrowing. 

The contents of this book provide basic informations on several fields 
of biology that have become life supporting disciplines. The students are 
exposed to fascinating fields such as Human Physiology, Medicine, 
Microbiology, Immunology, Bio-informatics, Environmental Biology, 
Genomics, Aquaculture, Medical Laboratory Techniques, Livestock 
management etc. More information related to these fields can be obtained 
from appropriate websites and reference books. Contents in this book have 
been prepared in such a way that the students can have a glimpse of several 
disciplines and might help them to decide on their future career and further 
given study plans. Further, the materials given are technical information that 
provide knowledge for to-day's living. 

T. Sargunam Stephen 

Chairperson 
Biology (Zoology) 
Text book writing committee. 



m 



Standard XII - Zoology Syllabus - (Theory) 

I : Human physiology - Nutrition : Introduction - Carbohydrates - Proteins - Lipids 

- Vitamins - Minerals - Water - Balanced diet - Calorie values (ICMR standards) - 
Obesity - Hyperglycemia - hypoglycemia - Malnutritions. 

Digestion : Enzymes and enzyme action - Brief account of following - Dental caries 

- Root canal therapy - Peptic ulcer - Hernia - Appendicitis - Gall bladder stone - 
Liver cirrhosis - Hepatitis. 

Bones and Joints (Major types) : Fractures - Dislocations - Arthritis - Rickets and 
osteomalacia - Orthopaedics - Gout. 

Muscles : Muscle action - Muscle tone - Rigor mortis - Muscle pull (hernia) - 
Isometric and aserobic exercises (Body building) - Myasthenia gravis. 

Respiration : Process of pulmonary respiration - Inspiration - Expiration - Exchange 
of gases at alveolar level - Control of respiration - Pneumonia - Pleurisy - Tubercu- 
losis - Bronchitis - Breathing exercises 

Circulation-Functioning of heart-Origin and conduction of heart beat. 
Artificial pacemaker-Coronary blood vessel and its significance-Myocardial 
infarction,Angina pectoris-Angiogram,angioplasty and coronary bipass surgery-Ath- 
erosclerosis-Heart attack-Heart block-ECG and Echo cardiograph-Heart valves Rheu- 
matic Heart Disease (RHD)-ICCU- Arterial and venous systems-Blood pressure-pulse 
rate-Heart transplantation Resuscitation in Heart attack (First Aid)-Blood 
components Function-Plasma-Corpuscles -Blood clotting-Anticoagulants-Thrombo- 
sis-Embolism-blood related diseases like polycythemia Leukemia-Lymph fluid. 

Physiological-Co-ordination Systems-Brain-Functioning of different 
regions-Memory-Sleep-Stroke- Alzhemier's disease-Meningitis/Brain fever Conditioned 
reflex-Electroencephalography-Right brain-left brain concept-Spinal cord-Functioning- 
Reflex action-CSF-Chemical co-ordination-Pituitary (Hormones of Adenohypophysis 
and their regulations)-Thyroid,Parathyroidal hormones-Insulin and Glucagon- Hormones 
of Adrenal cortex and Medulla-Reproductive Hormones-Problems related to Secretion 
Non secretion of Hormones. 

Receptor Organs-Eye-Focussing Mechanism & photo chemistry of retina-Short 
sightedness-Longsightedness-Optometry-Retinopathy-Cataract-Lens replacement- 
Nyctalopia-Eye infection-Conjunctivitis-Glaucuoma-Eye care-EAR-Hearing mechanism- 
Organ of corti-Hearing impairments and aids-Noise pollution and its importance-SKIN- 
Melanin-functions-Effect of solar radiations/UV-Skin Grafting-Dematitis-TONGUE-Gus- 
tatory reception. 

Excretion-Ureotelism-Urea Biosynthesis (Ornithine Cycle)-Nephron 
ultrafiltration,tubular reabsorption and tubular secretion-Renal failure-Dialysis Kidney 
stone formation-Kidney Transplantation-Diabetes. 



tv 



Reproductive system-Brief account of speramtogenesis - Oogenesis Menstrual cycle- 
In vitro fertilization-Birthcontrol 

II. Microbiology : Introduction-History of Medical Microbiology-The influence of Pas- 
teur Koch, and Lister- Virology, Structure, Genetics, Culture and diseases-AIDS and its 
control-Bacteriology-Structure,Genetics and diseases-Protozoan microbiology-Disease 
oriented-Larval microbiology-Diseases orinented-Life cycle of Taenia solium- 
Ascaris.Pathogenecity of Micro organism- Anti microbial resistance Chemotherapy. 

Ill.Immunology: Innate(Non-specific) Immunity- Anatomical Barriers-Physiological 
Barriers-Phagocytic Barriers-Lymphoidal organs -Thymus-Bursa of Fabricius-Periph- 
eral Lymphoid Organs-Lymph nodes-Spleen- Antibodies-Immunoglobulins-Regions of 
polypepetide chain-Transplantation immunology-Classification of grafts -Genetic ba- 
sis of organ transplants-Immune system disorder. 

IV. Modern genetics : Introduction-Scope-Human Genetics karyotyping Chromosome 
gene mapping, Recombinant DNA technology and segmenting. 

Genetic diseases-Human Genome project-Cloning-Transgenic organisms Genetically 
Modified Organisms (GMO)-Genetherapy-Bio informatics application-DNA sequenc- 
ing and protein structure. Biological database- 

V. Environmental science : Human population and explosion-Issue-Global warming 
Crisis Green House Effect-Ozone layer depletion Waste mangement-Biodiversiy con- 
servation (Biosphere reserves) Government and Non Govermental organisations in- 
volved-Energy crisis and Environmental impact-Poverty and environment-Fresh water 
crisis and management. 

VI. Applied biology : Livestock and Management-Dairy-Breeds of cattle-Milch breed- 
Draught breed-Dual purpose-Common diseases and control-Exotic and cross breeds- 
Techniques adopted in cattle breeding. 

Poultry-Farming techniques-Breeds. Farming methods-Poultry diseases-Economic value. 

Pisciculture-Fish farming-Edible fishes of Tamilnadu. 

Medical Lab Techniques-Stethoscope-Sphygmomanometer-Heamocytometer-Urine- 
Sugar analysis-ECG-'PQRST' wave-CTScan-Endoscopic (Laproscopic) techniques- Ar- 
tificial pacemaker- Auto analyser— 

VII. Theories of evolution : Lamarckism-Neolamarckism-Darwinism-NeoDarwinism/Mod- 
ern concept of natural selection-Species concept-Origin of species and Isolating Mecha- 
nisms 

VIII. Aquaculture : History-Prospects-Kinds-Pond structure-Bunds-Pond types-Loca- 
tion-Culture-Physics-Chemical factors-Food-Bionomics of cultivable fishes and fresh- 
water prawns-Induced breeding-Diseases parasites and control-Ornamental fishes - 
Culture-Feeding-Mariculture. 



SYLLABUS FOR PRACTICAL 

ZOOLOGY - (Long Version) 

STANDARD - XII 

1 . Qualitative test for carboydrates, proteins and lipids - 2 test each 

2. Test of urea in urine of a mammal 

3 . Rate of activity of human salivary amylase in relation to temperature and pH 

4. Study of perpared slides - Entamoeba, Scolex of tapeworm, mature 
proglottis, Red blood corpuscles, white blood corpuscles 

5. Models and specimens - Mammalian Brain / model, Eye model, Ear model, 

Mammalian Kidney - Nephron model, Heart model 

6. Instruments / Drugs - 

1 . Stethescope 

2. Sphygmomonometer 

3. An eye drop bottle having antibiotic fluid 

4. Eye lotion 

5. Bifocal eye lens 

7. Project Report 

1 . Visit to Medical Laboratory or Hospital or Research Laboratory 

2. Visit to a Dairy or Poultry or Fish farm 

3. Visit to a site havintg rain water harvesting 

vi 



ZOOLOGY 

CONTENTS 



PAGE 



1. HUMAN PHYSIOLOGY 001 



2. MICROBIOLOGY 116 



3. IMMUNOLOGY 142 



MODERN GENETICS 157 



ENVIRONMENTAL SCIENCE 181 



APPLIED BIOLOGY 215 



THEORIES OF EVOLUTION 270 



8. AQUACULTURE 286 



vn 



1. HUMAN PHYSIOLOGY 

Introduction 

Physiology is the study of functioning of organs and organ systems. 
All physiological activities are aimed at maintenance of homeostasis, 
living and reproduction. Homeostasis differentiates a living being from the 
non-living world. It provides the uniqueness for a self- duplicating, 
genomicized groups of organisms. Homeostatic mechanisms involve 
stabilizing an optimum level of water, minerals and other components of the 
body fluids and other thermal regulations. It is achieved by several 
bio-physical, bio-chemical processes, hormonal secretions and related 
metabolic modifications. 

The phenomenon of living is made possible due to several types of 
evolved organs and their well co-ordinated functions. The functioning of heart 
as a pumping organ being emotionally controlled is astonishing. The oxygen 
association and dissociation capabilities of blood pigments, cascading 
effects of minimal amount of hormones at molecular limits, the process of 
nervous conduction, analyzing and memory maintaining capacities of the brain, 
the holistic visual perception of the eye are all wonderful inventions of nature 
towards a simple process of living. 

The attainment of a simplified process of sexual reproduction for a 
complicated, genetically oriented mechanisms for sex cells production and 
procreation is stunningly marvellous. The orientation of reproductive 
strategies towards social, environmental and futuristic motives is highly 
precise and purposeful. 

Thus all the functionings of a living system are highly complicated 
mechanisms with a simple outlook. In the forthcoming chapter an attempt 
has been made to highlight defects in functioning, remedial attempts and 
life- style modifications. Proper treatment of such an objective will result in a 
voluminous work. Yet, a simple attempt has been made to provide the 
information. 



While going through the pages of this chapter, the learners may 
recollect the human anatomy learnt in the previous class. Knowledge and 
remembrance of anatomy will simplify an understanding of physiological 
processes. 

Nutrition 

The survival of all living organisms is due to several types of nutritive 
processes. The process of nutrition involves ingestion digestion, absorption 
and assimilation of food materials. The composition of nutrients vary in 
different types of feeding. However, for all living organisms, the nutrient 
comprises the following organic and inorganic components. They are 
carbohydrates, proteins, lipids, vitamins, minerals and water. Each 
component has a specific functional role. A well proportioned intake of nu- 
trients depends on several factors such as stage of growth, sex, health con- 
dition, bodily activities and environmental situations. 

Carbohydrates (Poly hydroxyaldehydes (or) ketones) 

A carbohydrate is composed of carbon, hydrogen and oxygen in the 
ratio of 1:2:1 (CH 2 0)n. They are of three types namely monosaccharides, 
disaccharides and polysaccharides 

Monosaccharides : 

These are the simplest form of carbohydrates being comprised of a 
single organic molecule. Depending on the number of carbon atoms they are 
classified into trioses, tetroses, pentoses, and hexoses. 

The trioses (C 3 H 6 3 ) are common intermediary products in 
carbohydrate metabolic processes. They play an important role in inter con 
version of biomolecules. (eg. glyceraldehydes). Pentoses (C 5 H 1() 5 ) like 
ribose and deoxyribose are the integral components of RNA and DNA 
molecules. The Hexoses(C 6 H 12 6 ) such as glucose, fructose and 
galactose are food components commonly consumed. 

Carbohydrates are commonly employed by the cells for providing 
energy. The energy metabolism happens through glycolytic 
processes involving oxidative, citric acid cycle. The energy liberated is stored 
in the form of ATPs (Adenosine triphosphate). 



Each gram of carbohydrate is capable of yeilding energy equivalent 
of 4.1 calories. 

Disaccharides 

These are the carbohydrates formed by condensation of two 
monosaccharide monomers. These are found in common food substances 
such as milk and sugar. There are three common disaccharides namely mal- 
tose, sucrose and lactose. They have the following composition 
Maltose D glucose + glucose 

(In germinating cereals) 

Sucrose (cane sugar) D glucose + fructose 
Lactose (milk) D glucose + galactose 

Polysaccharides 

These are complex carbohydrates formed by polymerisation of a large 
number of monosaccharides. Nature abundantly produces various types of 
polysaccharides. Several of them are structural components in the living world 
eg. chitin, cellulose. Starch molecules serve as storage food materials trap- 
ping enormous amount of energy. In food grains, starch is available as pectin 
and amylopectin molecules. Glycogen, a polysaccharide is found in liver and 
muscles. 

Proteins(Polypeptides) 

Proteins are nitrogenous compounds being made up of carbon, 
hydrogen, oxygen and nitrogen. Proteins also contain sulphur. In living 
systems proteins play an important role in the structural organisation eg., 
cell membrane, hairs, nails and muscles. Many of the proteins serve as 
enzymes. They are named as functional proteins. 

The building blocks of proteins are aminoacids. There are 
approximately twenty different types of amino acids, such as glycine, 
alanine, serine, valine, leucin, proline etc. The amino acids are classified as 
essential and non essential amino acids. Essential amino acids can not be 
synthesised in our body. Hence they should be made available through food. 
The essential amino acids are arginine, valine, histidine, isoleucine, 
leucine, lycine, methionine, phenylalanine, threonine and tryptophan. The non- 
essential amino acids can be synthesized in our body from other compounds. 
Such amino acids need not be added in the diet. 



A protein (or) a polypetide chain is formed of several amino acids 
linked with each other by peptide bonds. This linear arrangement is termed 
as primary organisation of a protein. However in most of the proteins, the 
straight chain structure gets complicated, into secondary, tertiary or quaternary 
stages. These levels are due to several other chemical bonds. The complicated 
nature of a particular protein is specifically required for its prescribed function. 
The amino-acids sequence and level of ogranisation is determined genetically. 
Hence the genome gets its importance due to its capability to produce, specific 
types of protein for bringing out genetical characteristics. 





Fig.1.1. Marasmas Fig.1.2. Kwashiorkar 

The daily requirement of protein, according to the Nutrition experts 
committee of ICMR (Indian Council for Medical Research) and WHO (World 
Health Organisation) is 1 gm per kg body weight. Reduction in the intake of 
protein leads to protein malnutritions, such as marasmus and kwashiorkar. 
In marasmas the child loses weight and it also causes severe diarrhoea and 
the body muscles get wasted. It will appear as though the bones are covered 
by the skin. In kwashiorkar there is a wastage of muscles. Face and feet will 
have oedema. The belly region will appear enlarged. 

Lipids 

Lipids are important cellular constituents. They are energy rich 
compounds. They form the most important storage food in the body. In our 
body, it serves as an insulating material. Cosmetically, the presence of limited 
amount of fat beneath the skin adds to beauty. Further, steroidal hormones 
are produced from certain lipids. 

The most common type of lipids are the simple lipids (or) 
triglycerides. They are naturally occurring substances (vegetable oils). In s 

4 



constituent of adipose tissue. Chemically a triglyceride is formed of glycerol 
and fatty acids. 

Fatty acids are of two types namely saturated and unsaturated 
fatty acids. The unsaturated fatty acids are capable of easier oxidative 
breakdown, hence poly unsaturated fatty acids(PUFA) are favoured for 
persons having high blood pressure and other related ailments. These fatty 
acids are abundent in sunflower oil and safflower oil. 

Each gram of lipid is capable of yielding 9.3 calories of energy. It is 
suggested that 25% to 30% of total calories should come from fat. 

Vitamins 

Vitamins are complex organic compounds, whose presence in trace 
amount in the food is essential for growth and other physiological activities. 
Vitamins do not have any energy value. However they are essential for 
controlling energy yielding processes. The identified vitamins are classified 
as A,B,C,D,E and K. Of these, vitamin B and C are water soluble in nature. 
Vegetables and fruits containing these vitamins if washed in water as cut pieces 
would loose them easily. Vitamin A,D,E and K, if consumed beyond 
required level may cause defects, commonly referred to as vitaminosis. 

Of the various vitamins, vitamin D or calciferol on exposure to sunlight 
can be synthesised by our body through the lipid compound called ergosterol, 
found below our skin. Hence it is known as 'sunshine vitamin' . 

The most important functions of vitamins include. 

1 . Physiological processes : Vitamin A plays a very important role in visual 
perception. Vitamin E might ensure fertility in animals. The clotting of blood 
is aided by vitamin K. Vitamin C provides immunity against infections and it 
may also support processes of growth. 

2. Maintenance of body tissues : The epithelial tissues of the body are 
maintained by vitamin A and B2. The growth of bones is ensured by vitamin 
D. Vitamin E plays a role in the rejuvenation of tissues. Nourishment to 
nerve cells is provided by vitamin Bj. The process of maturation of 
erythrocytes is due to vitamin B 1 2- 



3. Metabolic processes : The process of calcium and phosphorus 
metabolism happens due to the presence of vitamin D. Vitamin E remains an 
antioxidant. Vitamin B \ remains as a co-enzyme in tissue metabolism and it 
is found useful in the process of oxidation of glucose in CNS. Vitamin B2 is 
essential for carbohydrate metabolism. Niacin (vitamin B) plays a role as a 
co-enzyme and is essential for oxidation-reduction reactions. Normal 
metabolism of amino acids and fat are due to vitamin B5. Biotin (vitamin B) 
serves as a co-enzyme and co-factor in oxidative metabolism. Vitamin C 
activates certain intra-cellular enzymes. 

Vitamin Deficiency Ailments. 

Vitamin A 

1 . Atrophy of lacrymal glands of the eye and reduction in tear secretion 

2. Corneal epithilium becomes red and dry (xerosis). It may also 
become wrinkled and Keratinised (xeropthalmia). Appearance of 
Bitot's spot in the cornea might happen. 

3 . Cornea may get necro sed and get infected (keratomalacia) . 

4. May cause night blindness (nyctalopia). 

Vitamin D :- Defective calcification of bone, deficiency of vitamin-D, causes 
rickets in growing children and osteomalacia in adults. 

Vitamin E :- Rare in human, sterility in experimental animals. 
Vitamin K:- 

1 . Lack of vitamin K leads to defect in blood coagulation. 

2. In humans, vitamins K deficiency leads to haemorrhagic 
manifestations. 

Vitamin Bj:- 

Gross deficiency of vitamins B 1 , leads to a condition known as beri 
beri. Beriberi affects nervous and cardiovascular systems. In children and 
infants the onset is acute. 



Vitamin B2 : 

Loss of appetite and other gastro-intestinal symptoms, soreness and 
burning of lips, mouth and tongue. Fissures appear at edges of the mouth. 

Vitamin Niacin : 

Its deficiency leads to pellagra. The principal symptoms of pellagra 
include mental changes, (dementia) dermatitis and stomatitis. The tongue 
becomes smooth, red and painful. 

Vitamin B5: (Pyridoxine) 

In human pyridoxine deficiency causes dermatitis around eyes, nose 
and behind the ears. Fissures appear above the lips and angles of the mouth. 

Vitamin Bj2 •■ Its deficiency causes pernicious anaemia, typical sore 
tongue and several neurological problems related to the spinal cord. 

Vitamin C :- Its deficiency in the body leads to scurvy, a diseses charaterised 
by bleeding gums, loosening and falling out of teeth and intra muscular 
haemorrages. In the absence of this vitamin the collagen and connective 
tissue proteins are not synthesised properly. 

Minerals 

Along with complex organic substances, such as carbohydrates 
proteins and lipids, our body needs substances such as minerals, vitamins and 
water as accessory food factors. 

Of the minerals certain elements are found in greater concentration. They 
are sodium, calcium, potassium, magnesium, phosphorus, sulphur and chlorine. 
Certain other minerals are required in slightly lower concentration for performing 
useful functions. These include, iron, copper, zinc, cobalt, manganese, iodine and 
fluorine(trace elements). Of these minerals, larger portion of certain minerals are 
concerned with body building activities such as formation of bones and teeth 
(Calcium, Magnesium and Phosphorus). Trace elements and other minerals are 
useful in physiological activities such as oxygen transport (Iron), hormone 
synthesis (Iodine) and intermediary metabolism (Manganese, Copper, Zinc). Some 
of the elements remain as constituents of the body fluids (Chlorine, 
Sodium and Potassium). Presence of certain minerals is essential for 

7 



neuromuscular irritability (Magnesium, Sodium and Potassium), blood clotting 
(Calcium), cardiac functions (Potassium and Calcium). 

Water 

Water is a major costituent in the body of all mammals. The 
proportion of water in the lean body mass (mass of the body - fat content) is 
constant at around 7 1 to 78 % in animals including human beings. 

The total body water content varies with age, sex and body weight. 
In a new born child it is 85 to 90 % of body weight. In young adults it ranges 
from 55 - 60 %. 

Of the total body water, about 2/3 is found as intra-cellular fluid (ICF) 
and 1/3 as extra-cellular fluid (ECF). About 25% of ECF is the plasma of 
blood. 

The body water content is kept constant by maintaining a proper 
balance between water intake and loss. Intake of water happens through 
drinking of water and beverages, water in the food consumed and water 
generated during metabolism. The average water intake is around 2500 ml/ 
day (as water 1400 ml). 

Water loss happens through four routes. They are 

1. Urine (about 1400ml), 2. Expiration (400ml), 3. Through skin 
(600ml), 4. Loss in faeces (100ml) 

Role of water 

1 . It is an essential constituent of all the cells of the body. 

2. It serves as a transport medium for nutrients and excretory products. 

3. It serves as a site for chemical reactions. 

4. It is a valuable solvent for electrolytes, enzymes, hormones and 
vitamins. 

5. It plays a vital role in the maintenance of body temperature. 

6. It helps to maintain form and texture of tissues. 

8 



Balanced diet 

A balanced diet must have all food supplements in needed 
proportion. It should be preferred in such a way that normal growth, 
working capability, nitrogen balance and full calorie requirement can be 
maintained. While planning a balanced diet, the total calorie requirement of 
the individual is calculated and then the different components of the food are 
selected. Normally the calorie content of the food is fixed with an 
understanding that 10-15 % of calories are to be obtained from proteins, 
25 - 30% from fats and the rest from carbohydrates. 

Calorie values 

In nutrition and dietetics a calorie means the amount of heat required 
to raise 1 Kg water by 1°C. As per the Nutrition Expert Committee of ICMR 
(1968) the calorie requirements are prescribed for Indian Reference Man 
(IRM) and Woman (IRW). The IRM and IRW have following 
characteristics. 

IRM :- 25 years of age, 1.62 sq.mt of body surface, 55 kg body weight and 
remains healthy. 

IRW :- 25 years of age, 1 .4 sq.mt of body surface, 45 kg body weight and 
remains healthy. 

The calorie requirement for IRM and IRW depending on their nature 
of work is prescribed as follows 

IRM 

Daily activities Sedantary Moderate Heavy 

work work work 

A. Basal metabolism (BMR) 460 calories 460 calories 460 calories 
(8HrsofSleep) 

B. Nonoccupational 1220 calories 1220 calories 1220 calories 
activities (8 Hrs) 

C. Occupational 750 calories 1 100 calories 2200 calories 
activities (8 Hrs) 

Total 2430 calories 2780 calories 3880 calories 

9 



IRW 

A. Basal metabolism 
(8 Hrs of sleep) 

B. Non occupational 
activities (8 Hrs) 

C. Occupational 
activities (8 Hrs) 
Total 



354 calories 354calories 354 calories 



826 calories 826calories 826 calories 



610 calories 900calories 1800 calories 



1790calories 2080calories 2980calories 



While formulating and planning the diet for a person, his/her calorie 
requirement is assessed. This assessment is based on the requirement of IRM 
and IRW. It is adjusted according to age, weight, health and working 
conditions. Final prescription of food is provided based on the calorie value 
of each item of food. Due attention is given also for palatability and social 
food habit. Balanced diet for Indian adult male and female doing moderate 
work. 

Obesity 

Obesity is the storage of excess of body fat resulting in a significant 
impairment of health from a variety of diseases, notably hypertension, 
atherosclerotic heart disease and diabetes. A level of 10% above the 
standard weight, for subjects of same age and sex, is considered as obese. 

The degree of obesity is assessed by the body mass index (BMI). It 
is calculated as weight in Kg divided by the square of height in meters. For 
example, a 70 Kg person with a height of 180 cms would have a BMI of 
21.6 (70/1. 8 2 ). Normal BMI range for adults is 19 - 25. Men and women 
having BMI values above this range are considered obese 

Obesity may be due to genetic reasons, increased appetite leading 
to excessive intake of food than is needed by the body, endocrine causes 
and / or metabolic disorders. 



10 



Digestion 

The digestive system 

The digestive system includes the gastro-intestinal tract (mouth to 
anus) and the glandular organs. This system serves to transfer organic 
molecules, salts and water from the external environment to the body's 
internal environment. Most of the food taken into the mouth are large 
particles containing macromolecules such as polysaccharides and proteins. 
As such they cannot be absorbed by the intestinal wall. They must be 
dissolved and broken down into much smaller molecules. This process is 
named as digestion. Digestion is accomplished by substances called enzymes 
produced from the digestive glands. The enzymes are biocatalysts in the food 
breakdown process. 

The process of digestion 

Mouth :- In the mouth, digestion starts with chewing. It breaks up large 
pieces of food into smaller particles that can be swallowed without choking. 
It is accomplished by teeth, tongue, jaws and saliva. 

Chewing is controlled by the somatic nerves to the skeletal muscles 
of the mouth and jaw. Rhythmic chewing motions are reflexly activated by 
the pressure of food against the gums, hard palate at the roof of the mouth 
and tongue. 

Saliva :- The saliva is secreted by three pairs of exocrine glands, namely : 
the parotid, the submandibular and the sublingual. The daily secretion of sa- 
liva ranges from 1000 to 1500ml. It contains the organic substances amylase 
and mucin. The salivary amylase or ptyalin can act on starch. It converts 
cooked starch into the disaccharide, maltose. Mucin is a glycoprotein. It 
helps in the lubrication of food. The lubricated, swallowable form of food is 
called the bolus. The salivary secretion is controlled by reflex activities. 

Swallowing :- It is a complex reflex activity. It is controlled by the 
swallowing center in the medulla oblongata. During swallowing the soft 
palate is elevated, the larynx gets raised. The tongue forces the food back 
into the pharynx, the epiglottis closes the glottis and the food slowly passes 
into the oesophagus. 

11 



The oesophageal phase begins with relaxation of the upper 
oesophageal sphincter. In the oesophagus the food is moved towards the 
stomach by a progressive wave of muscle contractions that proceed 
downward to the stomach. Such waves of contraction in the muscle layer 
surrounding a tube is known as peristaltic waves. In the oesophagus one 
peristaltic wave takes about 9 seconds to reach the stomach. Due to 
peristaltic waves, swallowing can occur even while a person is upside down. 

The stomach 

It is a wide chamber, located below the diaphragm. The size and 
shape of the stomach depends on the food inside it. The stomach volume 
during feeding may increase upto 1.5 lit. Stomach's primary contractile 
action will produce peristaltic waves. Each wave begins in the body of the 
stomach and proceeds towards the pyloric region. The initial wave 
influences the muscles to close the pyloric sphincter, a ring of smooth muscles 
between the stomach and the duodenum. 

The inner wall of the stomach is lined with gastric glands. There are 
nearly 40 million glands engaged in producing gastric juice. The chief cells of 
the lining of stomach secrete enzymes and the parietal cells (Oxyntic cells) 
produce HC1 to create acidic medium for enzymes. 

The enzymes of the stomach are the pepsin and rennin. Pepsin is 
secreted in an inactive precursor form known as pepsinogen. The activity 
due to HC1 converts pepsinogen into pepsin. Pepsin hydrolyses the proteins 
into short polypeptide chains and peptones. It is most effective in an acidic 
environment. 

Proteins ^p olypeptides + peptones 

Rennin acts on soluble milk protein caesinogen and converts it into 
insoluble casein. In the presence of calcium ions casein is precipitated as 
insoluble calcium-casein compound (curds). 

Repeated peristaltic waves in the stomach help to soften the food. 
The frequency of contraction is determined by the basic electrical rhythm 
and remains essentially constant. It is also aided by neural and hormonal 
influences. The food leaves the stomach in the form of chyme and enters the 
upper small intestine at periodic intervals. 

12 



The small intestine :- It is about 5-7 metres long. It is divided into three 
segments namely the initial short segment the duodenum, the jejunum and 
the longest segment the ileum. 

The food is propelled down into the duodenum due to peristaltic 
action of stomach wall. The pyloric sphincter located at the junction of 
stomach and duodenum regulates movement of chyme. 



. 







J l ..neca>c 

} t V » i 
■ T J 



wrnmm^ 



.- % » m 






^ 



14444- 



\ 

Fig.1.3 Process of digestion 

The food in the small intestine is mixed with three juices namely bile 
juice, pancreatic juice and intestinal juice. 

Bile juice :- It is a brownish green, alkaline secretion of the liver. It is stored 
in the gall bladder and poured into the duodenum via the bile duct. The bile 
contains water, mucus, inorganic salts, cholesterol and bile salts. The bile 
salts emulsify fats and help enzymes like lipase to act upon fats. During 
emulsification, the bile salts convert bigger fat particles into smaller fat globules . 

Pancreatic juice :- It is an alkaline fluid (pH 7 to 8). It is transported to the 
duodenum through the pancreatic duct. It contains water, mineral salts and a 
variety of enzymes like : trypsin, chymotrypsin which are secreted in the 
form of inactive precursors trypsinogen and chymotrypsinogen. The 
precursors are activated by enterokinase of the intestinal juice, the amylytic 
enzyme amylase, the pancreatic lipase (steapesin), carboxypeptidase and 
nuclease. The enzyme trypsin hydrolyses proteins into polypeptides and 
peptones. 

trypsin 
Proteins > polypeptides + peptones 

13 



Chymotrypsin hydrolyses peptide bonds associated with specific amino 
acids like phenylalanine, tyrosine or tryptophan. It results in large peptides. 

_ . . chymotrypsin , . 

Proteins ^ large peptides 

Carboxypeptidase is an exopeptidase. It attacks the peptide bonds at the 

carboxyl end of the polypeptide chain resulting in di-, tripeptides and amino 

acids. The pancreatic amylase converts starch into maltose. The lipase acts 

on emulsified fat (triglycerides) and hydrolyses them into free fatty acids and 

monoglycerides. Monoglycerides may be further hydrolysed to fatty acid 

and glycerol. 

Intestinal juice: (Succus entericus) 

maltase 
Maltose — > glucose + glucose 

sucrase 
Sucrose — > glucose + fructose 

lactase 
Lactose > glucose + galactose 

peptidase 
Di, Tripeptides > aminoacids 

tvt , ■ , nucleotidase , , , 

Nucleotides > nucleoside + phosphoric acid 

^ T , . , nucleosidase 

Nucleoside > nitorgenous base + sugar 

Absorption and assimilation 

As a result of digestion, all macromolecules of food are converted 
into their corresponding monomeric units. Carbohydrates are broken into 
monosaccharides such as glucose and fructose. Proteins are hydrolysed into 
amino acids. Lipids get broken into glycerol and fatty acids. The simpler 
organic molecules along with minerals, vitamins and water enter into body 
fluids through the villi. 

The villi are small microscopic finger-like projections. Each villus is 
an absorbing unit consisting of a lacteal duct in the middle surrounded by fine 
network of blood capillaries. While the fatty acids are absorbed by the lymph 
duct, other materials are absorbed either actively or passively by the capil- 
laries of the villi. 

From the lumen of the alimentary canal absorbed food materials are 
carried to the liver through hepatic portal vein. From the liver, materials are 
transported to all other regions of the body for utilisation. This conversion of 
food into energy and cellular organisation is called as assimilation. 

14 



Dental Caries (Tooth decay) 

Tooth decay is the gradual erosion of enamel (the protective covering 
of the tooth) and dentine (the substance below the enamel). Plaque 
formation is the main cause of tooth decay. The most common sites of initial 
decay are areas where plaque easily becomes trapped, such as the grinding 
surfaces of the back teeth (which have minute grooves in them), the lateral 
(side) edges of adjacent teeth, and near the gum line. Plaque consists of food 
remains, salivary mucus by-products, and the bacteria that live in the mouth. 



■formation of plaque causing caries 
pulp cavity 




Fig. 1.4 Dental caries 

The bacteria feed mainly on the fermentable carbohydrates (simple sugars 
and starches) in food, and in breaking them down, create an acid that 
gradually destroys enamel, forming a cavity. If the process is not checked, 
the dentine gets eroded. The cavity gets enlarged enabling the bacteria to 
invade the pulp at the centre of the tooth and causes infection. 

Symptoms : 

Early decay does not usually cause any symptoms. The chief symptom 
of advanced decay is tooth ache, which may be aggravated by eating very 
sweet, hot or cold food. Decay may also cause bad breath. 

Treatment : 

Treatment consists of the drilling away the area of decay and filling the 
cavity with either dental amalgam (a mercury alloy) or cement (a composite 
resin that matches the colour of the tooth). In cases of advanced decay, it 
may be necessary to remove the infected pulp (the central, living part of a 
tooth) and replace it with a filling or to extract the tooth. 



15 



Root Canal Treatment 

It is a modern dental procedure to save a tooth in which the pulp (the 
living tissue within a tooth) has died or become untreatably diseased, usually 
as a result of extensive dental caries. 

Steps involved in Root Canal Treatment 

(1) A hole is drilled into the crown to remove all material from the pulp 
chamber. The root canals are then cleaned with fine-tipped instruments. The 
procedure is usually monitored by X-rays. 

(2) The cavity is washed out, and antibiotic paste and a temporary filling 
are packed into it. Some days later, the filling is removed and the canals are 
checked for sterlity. 

(3) When no infection can be detected, the cavity is filled with a sealing 
paste and/or tapering solid "point" made of gutta - percha resin mixed with 
zinc and bismuth oxides. The mouth of cavity is then sealed with cement. 

Peptic ulcer 

It refers to an eroded area of the tissue lining in the stomach or 
duodenum. The lining of stomach or duodenum are protected from the 
effects of HC1 by a layer of mucous. If the mucous layer is damaged, the 
acid may cause inflammation and erosion of the lining. It is known as peptic 
ulcer. Ulcer is of two types namely, duodenal and gastric. Of the two, 
duodenal ulcer is more common. It occurs in people in the age group of 
25 - 45 years. Gastric ulcer is more common in persons above the age of 50 
years. Peptic ulcer is a very common gastric ailment. 

Causes:- The ulcer is mostly due to infections by a bacterium called 
Helicobacter pylori. It may also be caused due to uncontrolled usage of 
aspirin or certain anti inflammatory drugs such as Ibuprofen. Ulcer may also 
be caused due to smoking, alcohol, coffiene and psychological stress. In 
severe peptic ulcer, upper digestive tract endoscopy is done to assess the 
extent of damage. A bleeding or perforated ulcer requires hospitalization. 
Common treatment of ulcer is aimed at healing the ulcer and preventing its 
recurrence. Life style changes such as giving up smoking and alcohol may 
be required. Anxiety, stress, strain and worrying should be avoided. 

16 



Hernia 

Hernia is commonly called "ruptures". A hernia occurs at a weaker 
region in the abdominal muscle. Due to increased pressure in the abdomen, 
the muscles become streched at the weak point, the pressure may be due to 
lifting heavy weights, continuously. Due to hernia, a visible bulge can 
develop. It will contain fatty tissues or part of the intestine. Abdominal 
hernias are common in men having heavy manual job. 

In hernia, a section of intestine may become twisted and get traped 
inside the bulge. The blood supply may be cut off. This is known as 
strangulated hernia. If it causes severe pain immediate surgery is needed. 
Hernia can occur in other areas of the body. 

Types of Hernia 

1. Inguinial Hernia - a portion of the intestine pushes through inguinial 
canal. This region is the weak spot. 

2. Femoral Hernia - It occurs in the part of the groin where the femoral 
vein and artery pass from the lower abdomen to the thigh, women who are 
over weight (or) who have several pregnancies may be affected. 

3. Umbilical Hernia - It develops in babies, behind the navel due to 
weakness in the abdominal wall. 

Hernia repair - For hernia often a simple surgery is needed. It is done by 
using local or general anaesthesia. 

Appendicitis 

It is the inflammation of the appendix, leading to severe abdominal 
pain. Appendix is a small blind ended tube found at the beginning of the 
large intestine. This disorder is very common among adolescents. It is more 
common in developed countries where diet contains less fibre food. The 
inflammation causes blockage. The closed end of the appendix beyond the 
blockage then becomes infected by bacteria. 

17 



The early symptoms includes sudden pain in the upper abdomen, 
nausea with or without vomitting. It may also cause mild fever. If a 
treatment is delayed the appendix may rupture and result in infection in the 
abdomen. The serious infection is called as peritonitis. The treatment 
involves the removal of appendix by surgery. 

Gall Stones 

These are the stones of various sizes and content that form in the gall 
bladder. The stone formation occurs in about 1/10 people, over 40 years of 
age. The Gall stones are formed by bile. Bile is made up of cholesterol, 
pigments and several salts. Any alteration in the composition of the bile can 
cause the formation of stones. The stones are mostly formed of cholesterol. 

There is no obvious reason for such a formation. However, obesity 
is a risk factor. High fat diet can also cause stone formation. In severe, 
complicated situations it may block the bile duct and cause jaundice. 

Hepatitis 

An acute hepatitis may happen due to variety of causes. Its 
manifestation is inflammation of the liver. Such inflammation may happen 
due to viral infection. Non-infectious hepatitis can happen due to excessive 
alcohol consumption. In early stage, the symptoms are not conspicuous. The 
symptoms include fatigue, poor appetitie, nausea, vomiting, fever and 
discomfort in upper right side of the abdomen. There is no specific 
treatment. People are usually advised to take rest, and avoid drinking of 
alcohol. 

Bones and Joints 

The adult human skeleton consists of 206 bones. The bones along 
with approximately 700 skeletal muscles, account for 50% of our body weight. 
Bones provide protection and support. When two or more bones join 
together, a joint or articulation is formed. Through several types of joints, 
they help in movements. 

18 



Fractures 

Fracture is defined as a break or crack in the bone. Trauma or injury 
to the bones of human body is getting increased with the development of 
industry and transportation. Trauma is the biggest killer and maimer of human 
beings all over the world. Hippocrates in the 14th century B.C. described 
the treatment of fractures and injuries to limbs. In India, the treatment of 
fractures to limbs is still carried out by traditional bonesetters. Modern 
methods of treatments are available. They are more scientific and 
appropriate. 

Types of fractures : 

1 .Green stick fracture : - This fracture occurs in the young bones of 
children. This fracture break is incomplete leaving one side of the cortex 
intact. 

2. Closed fracture :- A closed fracture is the one where the haematoma 
(blood clot)does not communicate with the outside. 

3. Open fracture (Compound fracture ) :- In this type, the fracture 
haematoma communicates with the outside through an open wound. It is a 
serious injury through which infectious germs may enter into the body. 





Closed 



Fig. 1.5. Types of fractures 

19 





Fig. 1.6. X-ray of fractures - Fracture dislocations 

4. Pathological fracture :-This type of fracture occurs, due to pathological 
lesions after a trivial violence in a weak bone. It may be due to 
hyperparathyroidism. 

5. Stress fracture :- It is a fracture occurring at a site in the bone, due to 
repeated minor stresses over a long period of time. 

6. Birth fracture :- It is a fracture occuring in the newborn babies due to 
injury during delivery. 

Mechanism of fracture : 

A fracture can be caused either by direct violence or indirect 
violence. Direct violence causes a fracture at the site of impact of the force. 
Indirect violence fracture is one that is transmitted to a bone away from the 
site of impact and producing the fracture there. 

Torsion produces spiral or oblique fracture. It is important to 
understand the mechanism of fracture as it helps in deciding the manoeuvres 

20 



for reducing further damages. When a man falls down from a building or 
from a coconut tree he sustains a fracture on bones and the spine. The 
fracture of bone is caused by direct violence and the fracture spine is caused 
by indirect violence. 

Healing of Bones in fracture : 

It involves three phases, viz., 

1. Inflammatory phase 2. Reparative phase and 3. Remodelling phase. 





— » 



fracture site 

tissue granulation 
Fig.1.7. Healing of bone in fracture 



callus 



1. Inflammatory Phase : - When a fracture occurs, at the site of fracture 
the blood vessels get broken and the blood fills up the gap of the bone. 
This blood clots to form a haematoma. This process takes place in one to 
two days. The soft tissue of this region undergoes inflammation. 

2. Repairative Phase : - A stage of callus is formed. It bridges the gap and 
establishes contact between the ends of fractured bone. The callus is 
nothing but granulation of tissues around the site of fracture. This phase 
takes place about eight to twelve weeks. (Fig. 1 .7) 

3. Remodelling phase : - Once the fracture is bridged by the callus tissue, 
the site of fracture undergoes remodelling by muscular and weight bearing 
stresses and slight deformity gets corrected by moulding. This remodelling 
takes up to one year. 

Physiotherapy and rehabilitation 

Physiotherapy is the therapaeutic exercise to make the limbs work 
normally. Therapaeutic exercise is carried out by physiotherapists under the 

21 



supervision of orthopaedic surgeon. The commom problem at the end of 
fracture treatment is the wasting of muscles and stiffness of joints. These 
two problems can be rectified by physiotherapy, by gradual exercises. 

Dislocation of joints 

Dislocation is the total displacement of the articular end of the bone 
from the joint cavity. The normal alignment of the bones becomes altered. 
Various factors are attributed for bone and joint dislocations. 

Dislocations are classified as 1. Congenital, 2. Traumatic, 
3. Pathological and 4. Paralytic. Congenital deformities are due to genetic 
factors or factors operating on the developing foetus. These are also called 
teratogenic or teratologic disorder. 

Traumatic dislocation is due to a serious violence. It occurs in the 
shoulder, elbow and hip. 

Pathological dislocation is caused by some diseases like 
tuberculosis. Tuberculosis of the hip may cause dislocation of the 
acetabulum. 

Paralytic dislocation occurs when a remarkable imbalance occurs 
on the muscle power, e.g. Poliomyelitis. 

Arthiritis 

Arthiritis is the inflammation of all the components and structures of 
the joints. It involves synovium, articular surfaces and capsule. 

Several etiological factors are attributed to the origin of arthirits 
(arthritogenesis). They are diet, psycho-somatic illness, infections, diseases 
and metabolic abnormalities, etc., Types of arthritis include. 

1. Infective arthiritis :- Infections such as Staphylococcal, Streptococcal, 
Gonococcal, Rheumatic, Small Pox, Tuberculosis, Syphilitic, Guinea worms, 
etc., can cause damages at the joints. It produces pain in joints. 

2. Rheumatic arthiritis : -It is a generalized disease affecting the 
connective tissues, of the whole body. It focalizes the involvement of 

22 



musculoskeletal system. It is an inflammation of synovial membrane. 
Rheumatic disease is considered to be of auto immune origin. It is due to 
immunological disorder against an unknown antigen.. 

3. Osteoarthritis (Osteoarthrosis) : - It is a degenerative condition of the 
joints, without any inflammatory process. Osteoarthiritis is a progressive 
process affecting the articular cartilage of aging joints. It is characterized by 
focal degeneration of the articular cartilage. In the later stage, the cartilage 
gets eroded and exposing the sclerosed bone. 

4. Metabolic arthiritis :- Metabolic arthiritis is due to metabolic 
disorders. This is a disease due to an inborn error of Purine metabolism. It 
is commonly called gout. This condition is characterized by the deposition 
of Sodium Urate crystals (uric acid) on the articular cartilage, synovial 
membrane and in the periarticular tissues. Gout is characterized by onset of 
pain swelling and reddening of joints. 

Rickets and Osteomalacia 

Rickets and Osteomalacia are caused due to inadequate mineralisation 
of the bones. Our skeletal system stores 98% of the calcium in the human 
body and hence calcium metabolism has a major influence on the structure 
and growth of bone. 




bow leg 
Fig.1.8. Rickets 



Rickets :- In this case, mineralization of bones is defective. The rickets caused 
by nutritional deficiency is called Nutritional rickets . In India, it is a 
common problem among the population below the poverty line. It is due to 

23 



Vitamin D deficiency. It occurs in children below four years. But it can 
afflict all age groups who have calcium and D deficiency. Vitamin D is 
associated with calcium absorption and deposition. Lack of calcium and 
vitamin D causes softening of bones and pliable deformity. In children the 
symptoms of rickets are bowed legs, knock knees, pigeon chest, 
broadening of wrist and ankles, protruberant abdomen, etc., 

The primary prevention of the Rickets, in the child begins by better 
nutrient of the pregnant mother, followed by supply of Vitamin D. Cod and 
shark liver oil are very good sources of Vitamin D. 

Osteomalacia : - In adults Vitamin D and Calcium deficiency leads to 
osteomalacia. This is characterized by bone pain and tenderness. It causes 
brittleness in the bones. 

Orthopedics 

Orthopedics deals with all bone deformities occurring in children as 
well as adults. The deformities may either be congenital or acquired. The 
former is caused by developmental abnormalities (teratogenic), the latter is 
caused by trauma or infections or by metabolic disorders. The corrective 
measures in the management of these disorders involve physiotherapy, splinting 
and use of appliances, traction procedure, plaster cast and wedging, 
manipulation under anaesthesia, surgical and neurological examination. 

Muscles 

Muscles are elastic in nature. They are capable of contraction in 
response to stimulus from the central nervous system. The muscle cells 
function like biological machines that convert chemical energy into 
mechanical work. The mechanical work involves various movements 
including vital processes like contraction of the heart and blood vessels. 
Approximately 40% of the body is skeletal muscle and almost 10% is smooth 
and cardiac muscles. 

Structure of a skeletal musclei 

A striated muscle is composed of many fibres arranged in 
bundles. The diameter of each fibre varies from 10 to 100 microns. The 

24 




Myofibril : « : a 




El Ji niJIIIIintaimiJMJIILTI 



r~gssr~i?H 



*„*.. 



S^-_jh--_-i : 



■ . r 



1 



/![ vrl/ryni I u lu rni j a i i ii i i| i m ra.a rTrr r.^rj 

— 3 ) 



I 

I , r i 

/mn Li 1 1 r ir rj r mi a rnrTfraiwtnnnmmJSr 
1 i ! ^ -X 

z * * ^ 

Fig.1.9. Ultra structure of muscle fibre 



25 



length of fibres ranges from 1 to 20mm. Each fibre is surrounded by a 
membrane, called the sarcolemma. 

Each muscle fibres is made up of 4 to 20 thread-like 
structures called myofibrils. They are parallel to each other. The myofibrils 
are 1 to 3 micron in diameter. In between the myofibrils, the sarcoplasm is 
present. A small segment of the myofibril is called as the sarcomere. 

Structure of sarcomere : 

When a sarcomere is observed under a microscope, we could see 
alternative dense (A band ) and light bands ( I band). The central region of 
the Aband is often less dense and is known as the "H Zone". The T band' 
is bisected by a dense narrow line, the Z line. Thus each sarcomere in- 
cludes repeating units between two Z lines in linear order as Z line, I band, A 
band, I band and next Z line. 

Electron microscopic studies have shown that the striations are due 
to the regular arrangement of 2 types of protein filaments. 'A band' contains 
a set of thick filaments formed of the contractile protein myosin. It may 
range upto 1 10 A° in diameter and 1.5 micron in length. 

The second set of thin filaments ( 50 A° diameter) overlap the long 
filaments in 'A band' . The second set of filaments extend partly in T band' 
and partly in 'A band' . These filaments are formed of a substance called 
Actin. 

Myosin, actin, tropomyosin and troponin are the four major proteins 
which constitute the contractile machinery of muscle fibre. The energy for 
muscle action is provided by ATP molecules. 

Mechanism of muscle contraction. 
I. Sliding - filament hypothesis. 

Hanson and Huxley proposed this hypothesis (1955). According to 
this hypothesis, the contractile unit of muscle is made up of two types of 
filaments i.e., myosin and actin. These filaments during contraction slide over 
one another. It has been observed that both at the time of contraction and 
stretching, the length of the 'A band' remains constant. The length of the T 
band' , on the other hand, changes in accordance with the length of the muscle. 

26 



— ■ I .. 



J-L ■ —- * 1- 



ii um - 



A band 



_!^J_ I IH— 



I ■ — 



-5- _." 

■lil i l ill 4- 



, I band 



i i i . i ii-i— 



_ ■ ■ — 

" ■ ■ — 




Fig. 1.10. Mechanism of muscle contraction 

Due to this, the Z discs are pulled together. Thus successive sarcomeres are 
pulled. This leads to the contraction of the muscle. 

ATP as the source of Energy for contraction :- For a muscle in action, 
energy is required. This energy is released by cleaving ATP molecules to 
ADP+ Pi. Greater amount of work is performed by the muscle, with greater 
amount of ATP that is cleaved. This energy binds with active site of actin 
filament to contract. 

Neuro muscular Transmission :- The muscles are innervated by 
myelinated nerve fibres that originate from the spinal cord. The nerve ending 
makes a junction, called neuromuscular junction. The nerve is connected 
at the midpoint of muscle fibre so that action potential in the fibre travels in 
both directions. When a nerve impulse reaches the neuro-muscular junction, 
a substance called acetylcholine is released. The acetylcholine induces muscle 
fibre for contraction. 

Initiation of muscle contraction :- Initiation of contraction of skeletal muscle 
begins with action potentials in the muscle fibres. These elicit electrical 
currents that spread to the interior of the fibre, where Ca ions are released 
from the sarcoplasmic reticulum. The Ca ions inturn initiate the chemical events 
of the contractile process. This overall process of controlling muscle 
contraction is called excitation. 

Maximum strength of contraction : The maximum strength of contraction 
of a muscle operating at a normal muscle length is about 3.5 Kg / Sq.cm. of 
muscle. 

27 



Changes in muscle strength : When a muscle begins to contract after a 
long period of rest, its initial strength of contraction may be as little as one 
half of its maximum strength. It gains strength after 30-50 muscle twitches. 
Weight lifters apply this to reach maximum capacity. 

Muscle Tone 

When the muscles are at rest, a certain amount of contraction usually 
remains. This residual degree of contraction in skeletal muscles is called 
muscle tone. The skeletal muscle tone is the result of nerve impulses from 
the spinal cord. These in turn are partially controlled by impulses transmitted 
from the brain. To some extent, the muscle tone is due to the muscle fibres 
itself. 

Muscle Fatigue :- ( muscle contraction is diminished) 

Prolonged and strong contraction of muscle leads to the state of muscle 
fatigue. This is due to muscle glycogen depletion and lactic acid accumulation. 
Fatigue probably results from inability of the contractile process and deficient 
metabolic process of the muscle fibre. 

However, experiments show, that transmission of nerve signals through 
the neuromuscular junction can occasionally diminish the prolonged muscle 
activity, thus further reducing the power of muscle contraction. It is a well 
known fact that non-supply of blood to the muscles leads to almost 
complete fatigue within a minute. This is due to non-supply of O, and 
nutrients to the muscles. 

Rigor Mortis :- Several hours after death all the muscles of the body attain 
a state of contracture called Rigor mortis. This is due to complete 
depletion of ATP in muscle fibres. The muscle remains in rigor, until the 
lysosome enzymes completely destroy all muscle proteins. This will take place 
within 15-25 hours after death. 

Muscle Pull 

Muscle pull is actually a muscle tear. A traumatic pulling of the fibres 
produces tear known as strain. This injury can occur due to sudden 
stretching of muscle beyond their point of elasticity. While some strains are 
the result of high velocity impacts, other types of pull can be due to repetitive 

28 



movements. When the muscles are being exerted over a long period of time, 
they become vulnerable to tearing from a simple change in the position of 
muscles. 

Back pain is a common problem, caused by muscle pull. This may be 
due to improper posture at the chairs. In these cases, the muscles are 
tightened over a long time, but the muscles may not tear until something as 
simple as reaching for a glass of water occurs. 

Types of muscle contraction :- 

There are 2 types of muscle contractions. 

1. Isotonic contraction: It involves muscle shortening as the myofilaments 
slide. This contraction produces normal movements, such as bending the 
knee, rotating the arms and smiling. 

2. Isometric contraction: It occurs when the myofilaments "spin their wheels" 
without moving, causing tension in the muscle. This is due to the muscles that 
are pitted against some more or less immovable object. 

Isometric and aerobic exercises 

In isometric exercise, muscles are moved through a short distance 
against a high resistance, as in pushing or pulling an immovable object. 
Isometric exercise is best for developing large muscles, whereas isotonic 
exercise has beneficial effects on the cardiovascular system. Isometric 
exercise-increases the thickness of the muscle fibres and their ability to store 
glycogen. 

Exercise : 

The muscle inactivity always leads to weakness and wasting of 
muscles. Muscles are no exception to the saying "use it or lose it". Regular 
exercise increases muscle size, strength and endurance. There are several 
exercises according to the needs and benefits. For example jogging or biking 
results in stronger, more flexible muscles with greater resistance to fatigue. 
Stamina formation is mainly carried out through aerobic activities, such as 
running and swimming. 



29 



Benefits of aerobic exercise: Physical exercise is a major contributor to 
health and can improve the body in three ways: more efficient heart, and 
lungs, improved muscle tone, and more supple joints. It is also essential to 
prevent obesity. Due to regular exercise, blood supply to muscle increases, 
it results in supply of more O,. Further aerobic exercises make overall body 
metabolism more efficient, improve digestion and enhances neuromuscular 
co-ordination. Heart beat enlarges, so that more blood is pumped out with 
each beat, fat deposits are cleared from the blood vessels and the lungs 
become more efficient in gaseous exchange. These benefits may be tempo- 
rary or permanent on the basis of regular and vigorous exercises. Aerobic 
exercises do not cause the muscle to increase in size, even though the 
exercise may go on for hours. Aerobic exercises increase the adaptability of 
muscles and give greater endurance to muscles. To gain good health, it is 
suggested that a total of at least 20 minutes per day, of moderate exercise, to 
burn around 200 calories (837 joules) a day, is required. Regular exercise is 
preferrable to occasional intense sessions. 

The bulging of muscles of a body builder or professional weight lifter 
results mainly from resistance or isometric exercise in which muscles are 
pitted against some immovable, or nearly so, object. Endurance and resis- 
tance exercises produce different patterns of muscle response, it is 
important to know what your exercise goals are. Weight lift will not improve 
your endurance for a marathon race. At the same time, Jogging will do little 
to improve your muscle definition nor will it make you stronger. Proper 
exercise for proper goal is necessary. 

Myasthenia Gravis 

This disease, affects one in 20,000 persons. It causes the person to 
become paralysed because of inability of neuromuscular junction to transmit 
signals from the nerve to muscle fibre. The muscles affected include those 
used in walking, breathing, chewing, and talking. A characteristic sign of the 
disease is drooping eyelids. Myasthenia gravis most often affects women 
between the ages of 20 and 30, but it can strike anyone after adolescence. 
It is believed that myasthenia gravis is an autoimmune disease in which 
patients have developed antibodies against their own acetylcholine activated 
ion channels. These antibodies are produced by thymus gland. If the disease 
gets intense enough, the patient dies of paralysis of respiratory muscles. The 

30 



disease can be cured by removal of the thymus and by a blood-cleansing 
process, called plasmaphoresis, that removes the destroying antibodies. 
About 10 per cent of the victims die. 

Respiration 

Respiration is a process by which oxygen reaches the body cells and 
is utilized by them in metabolism and carbon-di-oxide formed as a waste 
product gets eliminated. The real function of respiration is to provide the 
energy needed by body cells. Cells obtain energy by metabolizing glucose 
utilising oxygen. Hence they require a constant supply of oxygen. In 
addition, the waste products of the metabolic process, namely 
carbon-di-oxide must be carried away from the cells. The transport of 
oxygen and carbon-di-oxide between lungs and body cells takes place by an 
efficient cardio-vascular system. 

Process of pulmonary respiration 

Respiration includes several processes which are listed below 

(i). ventilation is the breathing in of air with more oxygen into the lungs 
(inspiration). It is followed by expulsion of air with more of carbon-di-oxide 
(expiration). 

(ii). Diffusion of oxygen from the alveoli into the blood inside 
surrounding capillaries. 

(iii). Transport of oxygen by the blood to the heart through the 
pulmonary vein. 

(iv). Distribution of oxygen by various arteries and their 
capillary network to all cells of the body. As the blood passes through tissue 
capillaries, it gives up oxygen (and nutrients such as glucose) to the body, 
tissues and picks up the waste products of cellular respiration (Carbon-di- 
oxide and water). 

(v). Exchange of the oxygen and carbon-di-oxide between the blood and 
body cells. With in body cells glucose and oxygen take part in a complex 
series of reactions which provide energy to power the cells. During this 
cellular repiration glucose is converted to carbon-di-oxide and water. 
(Enzymatic oxidation). 

31 



atmosphere 
C0 2 02 



ventilation (1) 




pulmonary circulation 



gas exchange (2) 



o 2 






right 
chamber 
of heart 



gas transport (3) 



C0 2 &~\ 



systemic circulation 



C0 2 






02 



left 

chamber 
of heart 



gas exchange (4) 



cells 



cellular respiration (5) 
Fig. 1.11. Exchange of gases at lungs and tissue 

32 



(vi). Transporting blood with carbon-di-oxide. Carbon-di-oxide is carried 
back in the blood to the heart then to the lungs where it diffuses into the 
alveoli and is breathed out of the body (External respiration). 

(vii) Exchanging of carbon-di-oxide with oxygen at the alveolar surface. 

(viii) Expiration of air with carbon-di-oxide from the lungs. 

Mechanism of Breathing : 

The process of inspiration and expiration happens due to pressure 
changes in the thoracic cavity. The thorax is an airtight compartment bounded 
by the sternum in front, the vertebral column at the back, the ribs encircling 
the sides and the diaphragm found below. The rib bones are provided with 
the two sets of muscles namely external and internal intercostal muscles. 
By the contraction and expansion of these muscles the volume of the thoracic 
cavity is reduced or increased. The floor of the thoracic cavity is completely 
closed by the diaphragm. The act of breathing is performed by expansion 
and contracton of the thoracic cavity. 

Inspiration :- Inspiration is the process by which fresh air is drawn into the 
lungs. It is an active process. The muscles participating in the inspiration 
process are external - intercostal muscles present in between the ribs and 
the diaphragm. 




thoracic volume increases 

alveolus 
rib cage 



diaphragm (lowers) 
Fig.1.12. Inspiration 




trachea 
intake of air 



diaphragm 



During quiet respiration, contraction of external intercostal muscle 
causes the ribs to move anteriorly and outwardly. This movement enlarges 
the cavity of the thorax by increasing it side to side and in dorso-ventral 
dimensions. 



33 



The contraction of radial muscles of the diaphragm leads to 
flattening of inelastic, dome shaped central part of the diaphragm. As a result 
of these muscular movements, the volume of the thoracic cavity is increased. 
This causes the air pressure within the lungs to fall below the atmospheric 
pressure. So air (tidal air) from outside passes through the air passage into 
the lungs to equalize the pressure. 

Expiration : Inspiration is followed by expiration. It is a passive process. 
Expiration is the process by which air is exhaled or blown out from the lungs. 
The expiration results when the volume of the thoracic cavity is decreased 
and air pressure in the lung is increased. The expiratory process involves the 
following movements. 




thoracic volume decreases 



diaparagm relaxes 



Fig.1.13. Expiration 




exhalation of air 



diaphragm 



1. The diaphragm relaxes and rises to resume the original dome shape. 

2. The ribs take their original position as a result of contraction of the internal 
intercostal muscles. 



Gaseous exchange in the alveoli 

Once the air is within the lungs the process of gaseous exchange 
begins. Capillaries of the pulmonary artery remains close to the wall of the 
alveloli. This enhances the exchange of gases. 

Oxygen carbon-di-oxide water vapour 



Inhaled % 
Exhaled % 



21.00 
15.7 



0.04 
3.6 



variable 
saturated 



34 



Po2=100mmHg 



venous blood 

(alveolar capillary) i ** 
PO2 = 40mmHg ( f 
PC02 = 46mmHg / 




alveolus 



arterial blood 
(alveolar capillary) 
P02 = 96mmHg 
V PCO2 = 40mmHg 



Fig.1.14. Exchange of gases in the alveolus 

Oxygen and carbon-di-oxide are exchanged across the alveolar 
membrane by diffusion from the site of higher to low partial pressure until the 
partial pressure of the two regions are equal. This process is a simple 
physical one which does not involve any secretary or active transport 
mechanism. 

In the atmospheric air there is a high concentration of oxygen 
20-95% (PO, 140mm Hg) while the proportion of carbon dioxide is low 
(0.04%). 

The alveolar P0 2 is about 100mm Hg and the P0 2 of venous blood 
is about 40mm Hg. This pressure gradient is sufficient for the transfer of 2 . 
The PC0 2 of venous blood is 46mm.Hg and that of alveolar air is only 6mm.Hg 
(l/10 th of O,), it is adequate for C0 2 transfer by diffusion. C0 2 diffuses 20 
times faster than 2 . 

Regulation of respiration : 

In the brain the medulla oblongata contains a respiratory center. This 
controls breathing. The respiratory center consists of an inspiratory center 
and an expiratory center. The axons from the nerve cells of these centres 
lead to the intercostals muscle through the intercostals nerves and the 
diaphragm via the phrenic nerves. These nerve fibres transmit impulses to the 
external intercostal muscles and internal intercostal muscles alternately. The 
walls of the alveoli have sense endings which are stimulated by changes in 
the tension of alveolar walls. 



35 



When the alveoli are stretched at the height of inspiration the 
receptors send stimuli to the expiratory center of the medulla through the 
vagus nerve which inhibits further inspiration. This sequence of events is called 
Herring - Breuer reflex. 

In addition the medulla contains a pneumotaxic center which is 
connected to the breathing centre and helps to ensure rhythmic breathing. 
During inspiration, the inspiratory part of the respiratory center sends 
impulses to the pneumotaxic center which responds by sending impulses to 
the expiratory part of the respiratory center. The expiratory center is then 
activated and so the inspiratory center is inhibited reflexly, respiratory rhythm 
is controlled in this manner by these centers in the brain. 

Pneumonia : 

Inflammation of the lungs due to infection is called pneumonia. 
Pneumonia is caused by viruses or bacteria. V/ra/ pneumonia is due to 
adenovirus, respiratory syncytial virus or a coxsackie virus. The most 
common bacterial pneumonia is Pneumococcal pneumonia. Pneumonia may 
also be caused by a mycoplasma (an organism that is intermediate between 
a bacterium and a virus) 

Symptoms and Signs : Symptoms and signs include fever, chills, shortness 
of breath and a cough that produces yellow - green sputum and occasionally 
blood. 

Treatment : The drugs prescribed depend on the causative microorganism. 
They may include antibiotic drugs or antifungal drugs. Aspirin or paracetamol 
may be given to reduce fever. Oxygen therapy and artificial ventilation may 
be required. 

Tuberculosis (TB) 

It is an infections disease, caused in humans by the bacterium 
Mycobacterium tuberculae. It was once common world wide and was a 
killer disease. People infected with HIV are highly susceptible to 
tuberculosis and the disease is becoming more common again in 
communities with high rates of HIV infection. 



36 



Causes :- Infection is caused by airborne droplets (produced by coughing 
or sneezing). The bacteria breathed into the lungs multiply to form an 
infected "focus". In a high proportion of cases, the body's immune system 
then halts the infection and healing occurs. The infection can also occur in 
intestines, bones and kidneys. 

Symptoms : The main symptom includes coughing (sometimes bringing up 
blood) chest pain, shortness of breath, fever and sweating (at night) poor 
appetite and weight loss. The main complications of tuberculosis of the lungs 
are pleural effusion. (Collection of fluid between the lung and the chest wall). 

Bronchitis 

Bronchitis is the inflammation of the bronchi, the air ways that 
connect the trachea (wind pipe) to the lungs, resulting in cough that may 
produce considerable quantities of sputum (Phlegm). Two forms, of the 
disease are recognized as acute bronchitis (sudden onset and short duration) 
and chronic bronchitis (Persistent over a long period and recurring over 
several years). Both are more common in smokers and in areas with high 
atmospheric pollution. 

Acute bronchitis : It is caused by viral infection or by the effect of air 
pollutants. Bacterial infection may cause acute bronchitis. Attacks occur more 
often in winter. Smokers, babies, the elderly and people with lung diseases 
are particularly susceptible. 

Chronic Bronchitis : 

It is a form of bronchitis in which sputum is coughed up on most days 
for atleast three consecutive months. The disease results in narrowing and 
obstruction of the air - ways in the lungs. It often coexists with another form 
of lung disease, emphysema (widening of alveoli). Chronic bronchitis and 
emphysema together are called chronic obstructive lung disease (COLD) or 
chronic obstructive airways disease. 

Causes : Pollution and smoking are the causes of chronic bronchitis. It 
stimulates the production of mucus in the lining of the bronchi. 



37 



Circulation 

The Circulatory System 

All cells of our body require constant nutrition and waste removal 
since they are metabolically active. Most of the body cells are located at 
some distance from the nutrient sources such as the digestive tract and sites 
of waste disposal such as kidneys. The cardiovascular system which 
consists of the heart, blood vessels and blood, connects the various tissues 
of the body. While the heart pumps the blood through the blood vessels, the 
blood delivers nutrients and collect waste products. 

Functioning of Human heart 

Heart is a pumping organ. It receives blood from different parts of 
the body through the veins that open through inferior and superior vena 
cavae and pulmonary veins. While the right atrium receives deoxygenated 
blood, the left atrium receives the oxygenated blood from the lungs. When 
the wall of the atria contract the right and left atria pump the blood into the 
right and left ventricles respectively. A pulmonary trunk arising from the 
right ventricle takes away the blood to the lungs for oxygenation. The left 
ventricle gives rise to an aorta, from which oxygneated blood is supplied to 
the coronary arteries and the systemic circulation of the body. 



aorta 



superior vena cava 

pulmonary trunk 
right atrium 
tricuspid valve 

inferior vena cava — 




pulmonary veins 
left atrium 
semilunar valve 



//VM 



right ventricle " \S \ I 

Fig.1.15. Functioning of human heart 



bicuspid valve 



left ventricle 



38 



The blood flow between the right atrium and the right ventricle is 
regulated by the tricuspid valve. The bicuspid or mitral valve regulates 
the flow on the left chambers of the heart. In the pulmonary trunk and the 
aorta, back flow of blood is prevented by a set of semilunar valves. 

Origin and conduction of heart beat 

During pumping action of heart, the heart muscles cause rhythmic 
contraction and relaxation of the heart chambers in a specific sequence. The 
rhythmic, sequential functioning of the cardiac chamber is maintained by 
sino-atrial node (SA node), atrio- ventricular node (AV node), bundle of His 
and Purkinje fibres. 



sino - atrial node 



atrio - ventricular node 




bundle of His 



purkinje fibre 



Fig.1.16. Origin and conduction of heart beat 

The S A node situated in the upper, lateral wall of the right atrium is a 
small, flattened strip of muscle fibre that is 1 .5cm x 3mm in size. The fibres of 
the SA node are closely associated with the muscles of auricles. SA node is 
capable of generating action potential that can travel throughout the auricles. 
The velocity of conduction is 0.3m/sec. The excitation from the SA node 
stimulates the AV node. The AV node in turn conducts the stimulus to bundle 
of His and Purkinje fibres. These myocardial fibres are found all over the 
wall of the ventricles. In the conduction of stimulus through the AV node and 
the fibrous system there is a delay in transmission. 

Cardiac cycle 

The sequential events occuring from the initiation of one heartbeat to 
the commencement of the next is called as one cardiac cycle. In this cycle, 
the contraction phase is called systole. The relaxation phase is the diastole. 

39 



A single heart beat comprises a systole and diastole in both atria and 
ventricles. 

Atrial systole : There is a continuous flow of blood into the right atrium 
through superior and inferior vena cava and coronary sinus. Simultaneously 
the left atrium receives blood from 4 plulmonary veins. There is a passive 
movement of nearly 70% of the blood. The remaining 30% is pumped into 
the ventricles by atrial contraction. 

Ventricular filling : When the valves in between atria and ventricles open 
nearly two-third of the ventricle is filled. Remaining space gets filled up by 
atrial contraction. 

Ventricular systole : As the atrial systole ends, the action potential 
generated by the SA node reaches the AV node and rest of the fibrous 
system. It causes contraction of the ventricular wall. Thus ventricular 
pressure results. The very strong ventricular pressure pumps the blood into 
respective arteries by causing the semilunar valves to open. 

Ventricular diastole : Soon after the blood leaves the ventricles there is a 
fall in the ventricular pressure. The semilunar valves close and the atrial 
valves open to begin the next cycle. 

Heart sound : The heart sound felt by a stethescope is caused due to the 
closure and opening of the valves. The generation of sound is rhythmic. The 
first sound is louder (lubb) and of longer duration (0.16-0. 90sec). It is due 
to closure of the atrioventricular valves at the beginning of the ventricular 
systole. The second sound is of shorter duration (dubb) (0. lOsec). It is caused 
at the end of the ventricular systole by the closure of semilunar valve. The 
heart beats at the rate of about 72-80 times per minute in adults. The ventricular 
systole causes a wave of distension due to blood flow. It is called as arterial 
pulse. It can be felt on the wrist. The pulse rate corresponds to rate of 
heartbeat. 

Coronary blood vessel and its significance 

There are two main coronary arteries the left and the right. The left one 
branches into the left circum flex artery and the left anterior descending artery. 
Right main coronary artery and the left coronary arteries branch off from the 
aorta, surround and penetrate the heart muscle. Arterioles and capillaries 

40 



branch off from the coronary arteries to supply heart muscle with oxygen 
rich blood. Deoxygenated blood drains into the coronary veins, which carry 
it back into the heart's right atrium. 

Damage to the coronary blood vessel or narrowing of the coronary 
vessel leads to coronary artery disease (CAD). Blood flow through the 
arteries is restricted, leading to damages of the heart muscle. Heart disor- 
ders like heart attack, myocardial infarction, the chest pain or Angina are 
usually caused by CAD. In many parts of the world mortality from 
coronary artery disease is rising due to changing life style factors. 

Myocardial infarction : Myocardial infarction is a coronary artery disease 
which involves sudden death of part of the heart muscle due to blockage in 
the coronary artery. It may cause severe unremitting chest pain. 

Causes : The coronary arteries that supply the heart muscle with fresh 
oxygenated blood become narrowed. This narrowing is usually due to an 
accumulation of droplets of fatty substances, like cholesterol. The fibrous 
cover of the fat deposit sometimes rupture, triggering the formation of a blood 
clot. If this blood clot blocks the artery, blood flow to an area of the heart 
muscle stops, causing myocardial infarction and leads to death of tissue. 

Symptoms : (1) Severe heavy crushing pain may spread up to the neck and 
in to the arms especially the left arm. (2) Sweating (3) Shortness of breath 
(4) Nausea and vomiting (5) Anxiety sometimes accompanied by fear of 
dying. 

About one in five people experience no chest pain in myocardial 
infarction. However, there may be fainting, sweating and pale skin. This 
pattern of symptom is known as "silent infarction". This type of infarction is 
common in people with diabetes mellitus or those with elevated blood 
pressure. 

Risk factors 

1 . Habitual cigarette smokers have a substantially increased risk of dying 
from myocardial infarction. 

2. High blood pressure is a major risk factor and the risk increases with 
higher pressure. 



41 



3. The risk of atherosclerosis and coronary artery disease increases 
dramatically in those who are more than 30 percent overweight. 

4. A raised blood cholesterol level increases the risk. A high fat diet is also a 
factor. 

5. Physical inactivity is also a major factor. 

Angina pectoris : Angina is a term that describes a strangling or constrictive 
pain. Angina has become synonymous with the heart disorder called Angina 
pectoris. This heart disorder refers to chest pain caused by insufficient 
supply of oxygen to the heart muscle, usually a result of poor blood supply. 
Angina pectoris usually occurs when the demand for oxygen is increased 
during exercise and at the time of stress. The pain usually comes on 
suddenly. The pain ranges from a tight ache to intense crushing agony. It lasts 
for 30 minutes or more and it is not relieved by rest. 

Causes (1). Inadequate blood supply to heart due to coronary artery 
disease such as atherosclerosis (2). Severe attack of anaemia which 
reduces the oxygen carrying capacity of blood. (3). Polycythemia (Increased 
number of red blood cells) which thickens the blood, causing it to slow its 
flow through the heart muscle. (4). Thyrotoxicosis (a disorder caused by 
excessive secretion of thyroxine) can precipitate angina pectoris by making 
the heart work harder and faster than its blood supply will permit. 

Angiogram 

Angiogram is a special contrast X ray and can be used to detect an 
abnormality in a blood vessel such as a narrowing of a large diseased artery. 

Coronary Angiography 

Coronary angiography is used to image the arteries that supply the 
heart muscle with blood. Angiography can image narrowed or blocked 
coronary arteries, which are not visible on a normal X-ray. A local 
anesthesia is injected and a fine flexible catheter is passed within the femoral 
artery, through the aorta and into a coronary artery. A contrast dye is 
injected through the catheter and a series of x rays taken. The procedure is 
painless. 



42 



Coronary Angioplasty 

Coronary angioplasty is an operation done to clear flow of blood 
when the coronary arteries are narrowed or blocked by fatty deposits with 
the help of a baloon catheter. Under local anesthesia, a guide wire is inserted 
through the femoral artery in the groin and up into the affected coronary 
artery. A baloon catheter is passed up the wire and the baloon is inflated in 
the narrowed area to widen it. Sometimes, a metal tube called a stent is 
inserted afterward. It keeps the artery open. 

Coronary bypass surgery is an operation to circumvent narrowed 
or blocked coronary arteries by grafting additional blood vessels to transmit 
blood flow. During this procedure the heart is temporarily stopped and blood 
circulation and oxygenation is taken over by a heart lung machine. 

Atherosclerosis 

Atherosclerosis is narrowing of the arteries caused by plaques on 
their inner linings . These plaques are composed mainly of fats deposited from 
the blood stream. They disrupt the normal flow of blood through the affected 
artery. Atherosclerosis encourages thrombus and embolus (fragment of blood 
clot). Men are affected earlier than women because women are protected 
by natural oestrogen hormones. 

Causes : Narrowing of the vessel is due to the development of raised patches 
called plaques. These plaques consists of athroma (fat and oil mixture), 
decaying muscle cells, fibrous tissue, clumps of blood platelets, cholesterol 
and calcium (abnormal blood clot) 

Risk factors : 

Cigarette smoking, Hypertension, male gender, obesity, physical 
inactivity, diabetes mellitus, heredity, aggressive personality. Severe effects 
of atherosclerosis is stroke (loss of blood supply to brain), heart attack (loss 
of blood supply to heart). 

Heart block 

Complete failure of the system that conducts electrical impulses from 
the upper to the lower heart chamber is called the heart block. Normally, 

43 



electrical impulses pass from the sinu auricular node to the atrio- ventricular 
node in the right atrium and then to the ventricle. In complete heart block, the 
impulses cannot reach the ventricle. This defective production of the sinu 
atrial impulses and its conduction in the heart is called heart block. 

Echo cardiography 

Echo cardiography is a technique that uses ultra sound waves to 
image the interior of heart. It is used to diagnose disorders of the heart and 
the heart valves. The test is usually done by using an ultrasound transducer 
(probe) placed on the skin of the chest directly over the heart. In some cases 
a small probe is passed down the oesophagus. 

Heart Valves : 

Heart valves are essential for precisely controlling the flow of blood 
in between auricles and ventricles and between the heart and major blood 
vessels. The valves are delicate pockets and their function is to prevent any 
backward flow of blood. The heart valve's functioning is vital for the 
efficiency of the heart as a pump. 

The opening and more particularly the closing of heart valves during 
each heart cycle are responsible for heart sounds. Any of the four heart valves 
may be affected by stenosis (narrowing) which causes the heart to work 
harder to force blood through the valve. Incompetence or insufficiency (leaki- 
ness) makes the valve unable to prevent backwash of blood. These defects 
cause characteristic heart murmurs which can be heard by a doctor. 

Rheumatic Heart Disease (RHD) 

It is a common form of disease found throughout the world. RHD is a 
crippling desease. Rheumatic fever develops due to an infection usually of the 
throat, caused by streptococcal bacteria. The condition is caused by the 
immune system attacking the body's own tissues in response to the infection. 
The symptoms of Rheumatic fever may include high fever, pain and swelling 
in bone joints. 

ICCU - (Intensive Coronary Care Unit) 

All major hospital in urban towns and cities have. Intensive 
Coronary Care Unit to care for people in a critical or unstable condition. 

44 



They require continuous monitoring. This unit has a wide variety of 
sophisticated equipments for constantly monitoring the condition of the 
seriously ill patient. The patient may be connected to a ventilator to maintain 
breathing. Body fluids and blood sugar levels are maintained by intra venous 
infusion of salts and glucose. Nutrients may also be supplied intravenously. 
Urine is collected through a catheter. Blood pressure is continuously 
monitored by an automatic sphygmomanometer. Heart rate and rhythm are 
monitored by an ECG machine. Results are often relayed to a central 
monitoring unit. Monitors are fitted with alarms to alert the staff if there is any 
dangerous variation from the normal range. 

Blood Pressure 

Blood pressure is the force exerted by the flow of blood against the 
walls of the main arteries while flowing through them. Blood pressure rises 
or falls as the heart responds to the varying demands made by the body 
during different activities such as exercise, stress and sleep. 

Two types of pressure are measured. Systolic (the highest) is the 
pressure created, by the ventricular muscle and the elastic recoil of the aorta 
(main vessel leaving the heart) as the blood flows through it. Diastolic 
pressure (the lowest) is recorded during relaxation of the ventricles between 
beats. It reflects the resistance of all the small arteries in the body and the 
load against which the heart must work. The pressure wave transmitted along 
the arteries with each heart beat is felt as the pulse. 

Blood pressure is measured using a sphygmomanometer. A healthy 
adult has a blood pressure reading of about 120/80 mm Hg (120 mm.Hg - 
systolic and 80 mm Hg - diastolic). This often rises normally with age to 
about 130/90 at 60. Abnormally high blood pressure is known as hyper ten- 
sion. Hyper tension is defined as the "Systolic pressure equal to or greater 
than 160 mm Hg and (or) the diastolic pressure equal to or greater than 95 
mm Hg". Abnormally low pressure is termed hypotension. 



45 



Intensive of hypertension 

Hyper tension puts a strain on the heart and blood vessels. Apart 
from increasing the risk of having a stroke or developing heart failure or 
coronary artery disease, high blood pressure may cause kidney damage and 
retinopathy (damage to the retina at the back of the eye). 

Causes 

Hypertension is linked with obesity and in some people to a high 
intake of salt, alcohol, smoking appears to aggravate the effects of 
hypertension. 

Preventive measures :- Alcohol consumption and smoking should be 
avoided. Obese persons should make an attempt to reduce weight through 
restriction of food intake and try regular exercise. The dietary intake of animal 
fat (milk, cream, cheese fatty meat and eggs) should be reduced. A restricted 
intake of salt is recommended. 

Heart transplantation involves replacement of a person's damaged or 
diseased heart by a healthy human heart taken from a donor in whom brain 
death has been certified. Heart transplantation in animals was first achieved 
in 1 959. The first human heart transplant was performed by Professor Christian 
Bernard in South Africa in 1967. 

Limiting factors for Heart transplant surgery 

1. Problem of timing : A heart transplant is possible only when a suitable 
donor heart is available at right time. 

2. Problem of fall-back system : If the heart is rejected (attacked by the 
body's immune system) the only hope for the patient is another transplant. 

3. Problem in the certification of brain death. 

The success of heart transplant lies in allowing doctors to certify brain 
death while the heart was beating. Heart is generatly removed for 
transplantation from a person certified for brain death by doctors. 



46 



Pulse rate 

The rhythmic expansion and contraction of an artery as blood is forced 
through it (pumped by the heart) is known as pulse. 

The pulse can be described in terms of its rate (number of expansion 
per minute) its rhythm, strength and whether the blood vessel feels hard or 
soft. 

The pulse rate is determined by counting the beats in a set period 
(minimum 15 to 20 seconds) and multiplying to give the beats per minute. 
The pulse rate usually corresponds to the heart rate which varies according 
to the persons state of relaxation or physical activity. 

Abnormal rhythm may be a sign of heart disorder. If the pulse feels 
weak, it may be a sign of heart failure, shock or an obstruction to the blood 
circulation. Weak or absent pulse in one or both legs is a sign of peripheral 
vascular disease. 

Cardio - Pulmonary Resuscitation 

Cardio - pulmonary resuscitation is the administration of the 
life - saving measures of external cardiac compression massage and mouth 
to mouth resuscitation (Artificial respiration) to someone collapsing with 
Cardiac arrest (Cessation of heart beat) 

It is vital to restore the circulation of oxygen carrying blood to the 
brain as quickly as possible because permanent brain damage is likely to 
occur if the brain is starved of oxygen for more than three to four minutes 

The blood :- 

The blood is a fluid connective tissue. It consists of liquid plasma and 
cells. The plasma makes up 55% of the total volume and 45% of cells or 
formed elements. The total blood volume in human female is about 4-5 litres 
and 5-6 litres in males. 

Plasma :- The blood plasma is a slightly alkaline fluid. It is straw coloured. 



47 



Composition of plasma 
Components 

1. Water 

2. Plasma proteins- Albumin 

Globulins 
Fibrinogen 

3. Ions - Na, K, Ca, Mg, CI , 
Fe, PO , H and HCO 2 

4 3 

4. Nutrients - Glucose, amino 
acids, triglycerides, cholesterol, 
vitamins. 

5. Waste products - Urea, uric! 
acid creatinine, ammonia J 

Bilirubin 
Lactic acid 

6. Gases 

Oxygen 
CO 
Nitrogen 

7. Regulating substances 

Hormones and Enzymes 



Functions 

- as a slovent and suspending medium 
for blood components. 

- Osmotic pressure. 

- Antibody formation 

- Blood clotting. 

- Osmosis, acid-base balance, 
-buffer etc., 

■ source of energy, building blocks 

■ enzyme activity. 

- excreted by the kidneys. 

■ breakdown product of erythrocytes 

- product of anaerobic respiration. 

- for aerobic respiration 

- waste product of respiration 
■inert gas. 

- body functions 



Blood cells or formed elements 

There are three types of blood cells or corpuscles. They are 

1 . Red Blood Corpuscles (RBC) or Erythrocytes 

These are circular, biconcave and non-nucleated cells. Males have 
about 5.2 million erythrocytes per cubic millimeter of blood (range : 4.2-5.8 
million). Females have about 4.5 million/mm (range 3.6-5.2 million). 



48 



Each disc shaped RBC is about 7.5 (im in diameter. Their main 
component is a pigmented protein, haemoglobin. It gives red colour to the 
blood. The haemoglobin transports C^- The oxygenated form of 
haemoglobin is called oxyhaemoglobin. 

Erythrocytes stay in circulation for about 120 days in males and 1 10 
days in females. They are manufactured in the marrow of bones such as ribs 
and vertebrae. They disintegrate in the spleen and liver. 

2. White Blood Corpuscles (WBC) or Leucocytes 

These are clear cells lacking haemoglobin. They are nucleated cells 
exhibiting amoeboid movement. They protect the body against invading 
micro-organisms and remove dead cells from the body. There are five types 
of leucocytes. 



- ... - 
lymphocyte 



♦J 



basophil 




'V. 

neutrophil eosinophil 

Fig.1.17. Different types of WBC 



a). Neutrophils - These are the most common type of leucocytes (60-70%) 
in the blood. Their nuclei can occur in more than one form. Hence they are 
called polymorphonuclear neutrophils (PMN). 

b). Eosinophils (0.5-3.0%) - They are motile cells that leave the circulation 
to enter the tissues during an inflammatory reaction. During allergy reaction 
their number increases. 

c). Basophils (0.1%) - They play a role in allergic and inflammatory 
reaction. They contain heparin which inhibits blood clotting. 

d). Lymphocytes (20-30%) - These are smallest leucocytes. They are more 
common in lymphatic tissues namely the lymph nodes, spleen, tonsils and 
thymus. Lymphocytes, called B-cells can produce proteins called 
antibodies that can get attached to the bacteria and destroy them. T-cells 

49 



protect us against viruses by attacking and destroying cells in which viruses 
are reproducing. 

e). Monocytes (1-4%) - These are largest leucocytes. They destroy 
bacteria, dead cells and cell fragments. During chronic infection their number 
increases. 

3. Blood Platelets or Thrombocytes 

These are minute fragments of cells that play a very important role in 
coagulation of blood. Their life expectancy is 5-9 days. 

Clotting of Blood or Haemostasis 

When a blood vessel is damaged, it results in coagulation or clotting 
of blood. A blood clot is a network of thread like protein fibers, called 
fibrin, that traps blood cells, platelets and fluid. 

The clotting depends on several proteins in the plasma. They are 
called coagulation factors. Normally these factors are in an inactive state. 
After injury they are activated to produce a clot. The activation can happen 
in three stages. 

Stage 1 - Formation of thrombokinase - Damaged tissues release a 
mixture of lipoproteins and phospholipids called tissue factor (TF) or 
thromboplastin. This factor in the presence of certain factors in the blood 
form a complex called prothrombinase or thrombokinase. 

Stage 2 - Formation of thrombin - During this stage soluble plasma 

protein prothrombin is converted into the enzyme thrombin by 

prothrombinase. Prothrombin synthesis in liver requires vitamin K. 

prothrombinase 
Prothrombin ^ thrombin 

Ca ++ 

Stage 3 - The soluble plasma protein fibrinogen is converted to insoluble 

protein, fibrin by thrombin 

,,., . thrombin _., . 
fibrinogen ►fibrin 

The fibrin forms the fibrous network of the clot. 

50 



Thrombosis 

The formation of a thrombus or blood clot within an intact blood 
vessel is called thrombosis. Clotting is a normal response that prevents bleeding 
when a blood vessel wall is injured. However thrombus formation is 
abnormal if it occurs in an intact vessel. 

A thrombus within an artery may block the artery preventing blood 
and oxygen from reaching the organ or tissue supplied by an artery. 

A thrombus that forms within one of the coronary arteries supplying 
heart muscle is known as coronary thrombosis. This is the cause for heart 
attack . 

A thrombus within arteries supplying the brain is known as cerebral 
thrombosis. It causes stroke. When a portion of a thrombus clot becomes 
fragmented and enters the circulating blood, it is called embolus. Embolus 
may block a circulation to vital parts resulting in serious consequences such 
as stroke. 

Co-ordination systems 

Nervous Co-ordination 

All living animals maintain a constant inner state, irrespective of 
changes happening in the environment. This phenomenon is named as 
homoeostasis. It is achieved due to coordination of response. The 
coordination is due to the animal body, acting as a self -regulating system 
capable of making appropriate responses to stimuli. 

The coordinating system of the body contains suitable structures for 
detecting stimuli, transmitting information and responding to stimuli. There 
are feedback mechanisms that ensure that degree of responses is 
related to the intensity and direction of the stimuli. 

Mammals have two main coordinating systems, namely the 
nervous system and the endocrine system. 



51 



Nervous system 

The neurons are the basic units of the nervous system. They help in 
conducting the stimuli in between the receptor organs - spinal cord, brain 
and effector organs. The neurons conduct the stimulus as electrochemical 
events. These sequential events involve migration of 'Na' and 'K' ions outside 
and inside the neuronal cells. This phenomenon is known as Sodium- 
Potassium pump. This sequence of electro chemical events is known as the 
impulse. 




Fig. 1.18. A synapse 

The junctions of neurons in nerve pathway are called the synapses. 
A synapse is formed between the bulb-like end structure of the axon called 
boutons and the cyton or dendrite of the adjacent neuron. At the junction 
there is a gap called the synaptic cleft, which is usually about 10 to 20 nm. 
At this point, transmission of stimulus happens through transmitter 
substances such as acetylcholine. 

In the nervous system the bundles of parallel axons of the nervous 
tissue having myelin sheath constitute the white matter. Collection of 
neurons having unmyelinated axons form the grey matter. 

The axons make up the white matter of the CNS for nerve tracts. 
They propogate action potentials. The grey matter performs integrative 
functions. The outer surface of the brain (cortex) and the central area of the 
spinal cord consist of grey matter. Within the brain, collections of grey 
matter form centers called nuclei. 



52 



The brain 

There are more than a thousand million neurons in the adult human 
brain. An estimate shows that the cerebral cortex alone has about 10 2783000 
synapses. Thus the brain is a complex organ. 

On structural and functional basis the brain can be divided into 3 
regions. They are (1). Fore brain, (2). Midbrain, (3). Hind brain. 

Fore Brain (Prosencephalon) :- This region of the brain comprises 
Diencephalon and the cerebrum. 

The diencephalon is formed of thalamus and hypothalamus. 

Thalamus :- It is the largest part of the diencephalon. This region contains a 
cluster of nuclei. Most of the sensory inputs are conducted to the cerebral 
cortex through the thalamus. Axons carrying auditory, visual and other 
sensory informations synapse with specific nuclei of this region. This 
region may also influence mood and general body movements due to strong 
emotions such as fear or anger. 

Hypothalamus :- 

This region contains small nuclei and nerve tracts. The nuclei called 
mamillary bodies are involved in olfactory reflexes and emotional responses 
to odours. The funnel shaped infundibulum from the hypothalamus 
connects it to the posterior pituitary or neurohypophysis . This region 
controls the secretions of the pituitary gland. 

The hypothalamus receives inputs from several sensory systems such 
as tongue, nose and external genitalia. It is associated with emotional and 
mood relationships. It provides a relaxed feeling. Feeling good after a meal, 
rage and fear are also due to this region. It also coordinates responses to the 
sleep- wake cycle with other areas. 

Cerebrum :- 

It is the largest part of the brain. It weighs about 1400g in males and 
1200g in females. Larger brains are normally associated with larger bodies 
and not with greater intelligence. 

53 



The grey matter on the outer surface of the cerebrum is the cortex. It 
forms clusters deep inside the brain called nuclei. The inner part of the brain, 
in between the cortex and the nuclei has white matter named as 
cerebral medulla. 



hand skills 

head rotatio 
eye movement 

motor cortex 
(controls many 

voluntary muscles) 

premotor area 
(motor functions 
are organised) 

speech area 

FRONT 

frontal lobe 




sensory cortex 
(receives information from skin) 

arietal lobe 

(sensory association areas) 



ccipital lobe 
(visual association 
areas) 

BACK 



primary visual area 



temporal lobe 
auditory association areas 



Fig. 1.19. Cerebral cortex - functional areas 



Cerebral cortex :- 



The cortex contains several primary sensory areas. These areas 
include taste area, primary auditory cortex for processing auditory stimuli, 
visual cortex for perceiving visual images and areas for other cutaneous 
sensations. 

The cortical areas adjacent to the primary sensory centers are called 
the association areas. These areas are involved in the process of 
recognition. For example the sensory stimulus from the retina of the eye 
reaches the visual association area of the cortex. Here the visual 
information is compared with past experiences. Further this area has 
connections with other parts of the cortex, which influence decisions. Thus 
visual information is judged several times. This may be one of the reasons 
why two people who witness the same event can present somewhat 
different versions of what happened. 



54 



The primary motor area of the cortex controls many voluntary 
movements, especially the finer motor movements of the hands. Muscle groups 
such as facial muscles, that have many motor units have greater innervation. 
They are represented by a large area of the motor cortex. 

Anterior to the primary motor area are the premotor area. It is the 
staging area in which motor functions are organized before they are 
initiated in the motor cortex. For example, if a person decides to lift a hand, 
the neurons of the premotor area are stimulated first. This area determines 
the order and the degree to which the muscles must contract. 

The prefrontal area provides motivation and foresight to plan and 
initiate movements. This area is well developed only in primates and 
especially in humans. Our emotional behaviour and mood are controlled by 
this area. 

The midbrain or Mesencephalon :- 

The roof of this region contains four nuclei. The nuclei form mounds. 
They are collectively called corpora quadrigemina. It is formed of 2 
superiour colliculi or mounds and 2 inferior colliculi or mounds. The 
superior colliculi are involved in visual reflexes. They control eye and head 
movements. They aid in visual tracking of moving objects. The inferior colliculi 
are involved in hearing. 

The hindbrain or Rhombencephalon :- 

This part of the brain comprises Cerebellum, Pons and Medulla 
oblongata. 

Cerebellum :- 

This region communicates with other region of the CNS through three 
large nerve tracts called the cerebellar peduncles. 

The cerebellum consists of following three parts 

Parts Control 

1 . flocculonodular balance and maintenance 

of muscle tone. 

55 



2. vermis - anterior part motor coordination and muscle tone. 

3 . vermis - posterior part and fine motor coordination and 
lateral hemispheres muscle tone. 

Cerebellar disfunction may cause decreased muscle tone, imbalance and lack 
of co-ordination. 

Pons :- 

This region relays information from the cerebrum to the 
cerebellum. It also contains sleep center and respiratory centers. These 
centers along with medulla help to control respiratory movements. 

Medulla oblongata :- 

It is the most inferior part of the brain stem. It acts as a conduction 
pathway for both ascending and descending nerve tracts. The nuclei inside 
medulla oblongata function as centers of several reflexes involved in the 
regulation of heart rate, blood vessel contractions, breathing, swallowing, 
vomiting, coughing and sneezing. 

Memory 

The term 'memory" denotes a specific brain function of storing and 
retrieving of informations related to experiences. The duration of memory 
varies from few seconds or hours, to several years. 

Types of memory :- 

1. Sensory memory :- It means the ability to retain sensory signals in the 
sensory areas of the brain for a short interval of time following the actual 
sensory experience. This is the initial stage of memory process. 

2. Primary memory :- It is the memory of facts, words, numbers, letters or 
other information. The information in this memory is instantaneously made 
available so that a person need not search through his or her mind for it. 

3.Secondary memory :- It is the storage in the brain of information that can 
be recalled at some later time(hours, days, months or years later). This is 
also called long-term memory, fixed memory or permanent memory. 

56 



Physiology of memory :- Certain anatomical, physical or chemical changes 
occur in the pre synaptic terminals (a part in the neuron) or perhaps in whole 
neurons that permanently facilitate the transmission of impulses at the 
synapses. 

All the synapses (nerves junctions) are thus facilitated in a thought 
circuit. This circuit can be re-excited by any one of many diverse signals at 
later dates thereby causing memory. The overall facilitated 
circuit is called a memory engram or a memory trace. 

Amnesia :- Amnesia means memory loss. It is the inability to recall 
memories from the past. 

Sleep 

Sleep is defined as a state of unconsciousness from which a person can 
be aroused by appropriate sensory or other stimuli. 

Types of sleep :- 

During each night a person goes thorugh two stages of sleep that 
alternate with each other. They are (1) Slow wave sleep and (2) REM sleep. 

Slow wave sleep :- In this type of sleep the brain waves are very slow. 
Though this sleep is frequently called "dreamless sleep", dreams actually occur 
very often and even nightmares occur during this sleep. During this sleep the 
process of consolidation of the dreams in memory does not occur. This sleep 
is highly useful in decreasing blood pressure, respiratory rate and basal 
metabolic rate. 

REM sleep or Rapid eye movement sleep :- In a normal night sleep, 
REM sleep lasting 5-30 minutes usually appear on an average 
every 90 minutes. It is usually associated with active dreaming. The muscle 
tone throughout the body is exceedingly depressed during this sleep 
indicating strong inhibition of the spinal projections from the reticular 
formation of the brain stem. 

The heart rate and respiration usually become irregular, which is 
characteristic of the dream state. During REM sleep, the brain is quite 
active. But, the brain activity is not channeled in the proper direction for 
persons to be aware of their surroundings and therefore to be awake. 

57 



Physiological effects of sleep :- Sleep restores both normal sensitivities of 
nervous system and "balance" among the different parts of the central 
nervous system. Due to good sleep arterial blood pressure falls, pulse rate 
decreases, skin vessels dilate, muscles fall into relaxed state and overall 
metabolic rate of the body falls by 10-30 percent. 

Stroke 

"Stroke is a rapidly developed clinical sign of focal disturbances of 
cerebral function lasting more than 24 hours or leading to death". (WHO) 

Inspite of the presence of factors inhibiting the coagulation of blood 
within vessels, clotting may occur at times. Such clots frequently are formed 
in veins than in arteries. The blood clot or thrombus formed in the streaming 
blood is called thrombosis. A clot in the cerebral vessel is called stroke or 
cerebral thrombosis. Stroke may be caused due to vascular occlusion, which 
is a blockage in the cerebral artery. The occlusion and stroke lead to 
infarction. The infarction leads to abnormal symptoms in the brain. 

Vascular occlusion is of two types viz., Thrombotic and embolic. An 
embolus is a portion of the thrombus clot that becomes detached and enters 
into circulating blood. An embolus may block the circulation to vital parts 
leading to serious consequences. 

Brain haemorrhage: Haemorrhage or bleeding of brain vessels may be 
caused by hypertension which results in bursting of blood vessels or due to 
aneurysm wherein the arterial wall bulges and forms a sac like structure and 
ruptures later. The stroke and the haemorrhage are also due to vascular 
malformations. 

Stroke causes both physical; and mental crippling. It is a worldwide 
health problem. It can occur at any age. Several risk factors may lead to 
stroke and brain haemorrhage. They are cardiac abnormalities, diabetes, 
elevated blood lipids, hypertension, obesity, smoking and stenosis (narrowing 
of valvular orifice), etc. 

One can control stroke by controlling the above risk factors. 

58 



Alzheimer's Disease 

Alzheimer's disease is otherwise called Chronic brain syndrome. 

It is characterized by progressive loss of memory followed by general loss 
of cognitive functions and death. This disease becomes more and more 
prevalent among aged persons. Occasionally people develop the disease 
before 50 or even before the age of 40. It affects less than 5 per cent of the 
population between 65 - 74. In the aged people beyond 80 almost 50 per 
cent are affected invariably. 

Alzheimer's disease is associated with the atrophy of cerebral 
cortex. Neurons undergo degeneration. In the damaged regions, plaques 
formed by the degeneration of axons and dendrites, appear. 

Alzheimer's disease is commonly attributed to genetic mutation. 
People with Down syndrome are invariably affected with this disease. It is 
presumed that atleast two or three genes in chromosome 21 are linked to 
this disease. However genetics is not the only etiological factor, for this 
disease. 

Meningitis (Brain fever) 

The term Meningitis refers to the inflammatory condition of the brain 
membranes and the sub-arachnoid space. Meningitis may be caused by 
bacterial infection, or viral infection or fungal infection. The clinical 
symptoms of meningitis include headache, photophobia, irritability, stiffness 
of the neck, fever and other neurological symptoms. 

Conditioned reflex 

The Russian Physiologist Ivan Pavlov first demonstrated 'the 
conditioned reflex' phenomenon. The cerebral cortex controls the 
conditioned reflexes. It is also called the classical conditioning, in which a 
stimulus comes to elicit a response similar to the response produced by some 
other stimulus. 

In his experiment, Pavlov presented a dog with a sound of a bell 
(Neutral stimulus) followed by meat (Unconditioned stimulus). This 
combined stimuli stimulated the dog to salivate (unconditioned response). 
After many such conditioned pairings the sound alone (Conditioned 
stimulus) would stimulate the dog to salivate (Conditioned response - CR). 

59 



The bell sound initially called the neutral stimulus which after a 
number of trials pairing with the unconditioned stimulus (UCS) viz., the meat 
piece, becomes the conditioned stimulus. Similarly the salivation of the dog 
during the initial trials of pairing (NS + UCS) is called Unconditioned Re- 
sponse (UR). This unconditioned response later on becomes designated into 
a conditioned response (CR). It will be elicited just by bell sound (CS). 

The conditioned reflexes are developed in animal's life in association 
with previously established reflexes. This is the basis of learning and memory. 

Electroencephalography (EEG) 

The tissues of the cerebral cortex consists of a vast range of neuronal 
elements. The brain tissue is characterized by a continuous rhythmic 
oscillation of electric potential. EEG is a device to record electrical activity 
of the brain via electrodes attached to the scalp. It displays a net average of 
all the neuron's potential. EEG yields information about the brain function in 
health and disease. It provides data about brain functions during various 
functional or behavioral activities such as sleeping or waking states. It is also 
used in the diagnosis of brain disease such as tumour, lesions and also in 
epilepsy. 

Right and Left brain concept 

In the cerebral cortex, the left hemisphere is connected to the skin 
receptors in the right half of the body. It also controls the muscles on the right 
side of the body. 

The right hemisphere is connected to the sensory receptors on the 
left half of the body. Further, it controls muscles on the left side. Both the 
hemispheres are also connected to the eyes. The sensory nerve tracts of the 
left eye is connected to the right hemisphere and the right eye to the left 
hemisphere through the optic chiasma. Thus the left half sees the right half of 
the world while the right half sees only the left half of the world. 

The left and right hemispheres exchange information through a set of 
axons called the corpus callosum, and also through anterior commissure and 
hippocampal commissure. The two hemispheres have their own specific 
functions and the above division of functions or labour between the two 
hemisphere is called 'lateralization' . 

60 



The corpus callosum enables the right and left half of the brain to 
operate cooperatively, instead of independently. The anterior commissure 
plays an important role in unifying the emotional responses of two sides of 
brain. Damage to the corpus callosum blocks the exchange of information 
between the two hemispheres. 

The left brain is concerned with language, number skills, reasoning, 
spoken language, scientific skills and right hand control. 

The right brain is concerned with art awareness, imagination, visual 
functions, emotions, music awareness, 3D forms and left hand controls. The 
left brain is meant for analytical tasks while the right brain is for creative 
tasks. 



Spinal cord functioning 

The spinal cord remains as a connecting, functional nervous structure 
in between the brain and sensory / effector organs. The sensory inputs 
received by sense organs are conducted towards appropriate regions of the 
brain. Similarly from the brain motor sensations are transmitted towards 
effector structures. Further as the brain, the spinal cord can effect motor 
initiation and bring about an effect. This activity is known as reflex action. 

Reflex action 

Reflex action is the spontaneously involuntary response caused due 
to stimulation of receptor organ. E.g. The quick closure of eye lid when 
some object touches the eyelashes.; the sudden withdrawl of hand when the 
hand touches hot pan. 



spinal cord 



motor route 



hot pan 




sensory route 



Fig. 1.20. Route of reflex action 

61 



A reflex action is an involuntary process and does not involve the 
intervention of consciousness. The anatomical basis of reflex action is the 
reflex arc. It is a nerve chain between receptor organ and effector organ. 
The reflex arc has the following route. 

Sensory organ —> sensory or afferent neuron —> grey matter of the 
spinal cord — > intermediary or relay neuron — > efferent or motor neuron —> 
effector organ. 

Cerebro Spinal Fluid (CSF) 

The ventricle of the brain and the central canal of the spinal cord 
contain, a clear fluid similar to plasma called cerebrospinal fluid (CSF). 
CSF is formed by a group of cells called the choroid plexus located inside 
the four ventricles. In human the volume of CSF is 150 ml and the rate of its 
secretion is 550 ml/day. 

Functions: 

1 . CSF cushions the brain against mechanical shock when the head moves. 

2. It acts as a protective covering for the CNS and confers buoyancy to 
brain. 

3. The CSF also provides a reservoir of hormones and nutrition for the brain 
and spinal cord. 

4. It acts as a mechanical buffer. Remaining inside and outside the CNS, it 
equalizes the mechanical pressure. If the intracranial pressure tends to rise 
the CSF is pressured out. If the pressure tends to fall, more CSF is retained. 

Chemical co-ordination 

The two major systems of the human body that coordinate, regulate 
and integrate almost all physiological functions are the nervous system and 
the endocrine system. The information transmitted by the nervous system in 
the form of electric impulses is conducted rapidly in the neurons. The signals 
from the endocrine glands or ductless glands are communicated by means of 
chemical substances called hormones. The hormones are secreted into and 
carried by the blood stream from their point of origin to the target organs or 
tissues. In the target tissues, the hormone action is manifested. 

62 



A hormone may be defined as a chemical substance synthesized by 
the cells of endocrine glands and carried by blood to the site of action where 
it exerts its physiological effects. Hormones are considered as chemical 
messengers. 

Functions of Endocrine glands: 

Endocrine glands play an important role in maintaining the constancy 
of internal environment (milieu interior) and hormones integrate and 
regulate various physiological functions. They regulate the general 
metabolism viz., the metabolism of carbohydrates, proteins, fats, minerals 
and water. The endocrine glands also control the reproductive functions of 
animals. The adrenal hormones prepare the body to meet emergency and 
stressful situations. The hormones are also responsible for intercellular 
communication . 

Each endocrine gland may secrete excess quantities of its own 
hormone. However, once the normal physiological response is over, this 
information is fed back to the endocrine gland. As a result, its secretion 
decreases or inhibited. Conversely, if the secretion of the hormone is 
subnormal and the physiological effects or responses are reduced, the 
information is taken to the gland and it secretes the hormone at an increased 
rate. Thus, homeostatic equilibrium is restored. 

Hypothalamus 

Hypothalamus represents the central part between the nervous 
system and endocrine system. Though pituitary is designated as the master 
gland controlling the functions of other endocrines, the pituitary itself is 
controlled by the hypothalamus. The above control is effected by means of 
releasing hormones or factors and inhibitory hormones or factors. The 
hypothalamus is connected to the posterior lobe of pituitary by the 
neural tissue and to the anterior lobe of pituitary by the epithelial tissue. 
The releasing factors from the hypothalamic cells reach the anterior pituitary 
through their axons. The hormones from the pituitary enter the blood stream. 

Pituitary gland: 

The Pituitary gland is otherwise called the hypophysis. It is located at 
the base of the brain. It is approximately 1 cm long, 1-1.5 cm wide and 0.5 

63 



cm thick. It weighs about 500 mg. Anatomically the pituitary gland is divis- 
ible into anterior adenohypophysis and posterior neurohypophysis. The 
adenohypophysis consists of three lobes or zones namely, Pars intermedia, 
Pars distalis and Pars tuberalis. The anterior lobe or adenohypophysis is 
embryologically derived from the roof of the mouth as a dorsal pouch. The 
neurohypophysis on the other hand, originates from the floor of 
diencephalon, as a downward growth. 

<5 



infundibular stalk 



neurohypophysis 




adenohypophysis 



Fig.1.21. Pituitary gland 



The hormones of anterior pituitary: 

The adenohypophysis is responsible for the secretion of six trophic 
hormones or tropins. They are growth hormone or somatotropic 
hormone (GH/STH), thyrotropic hormone or thyroid stimulating 
hormone (TSH), Adrenocortico tropic hormone (ACTH), Follicle 
Stimulating Hormone (FSH), Leutinizing hormone (LH) and Prolactin 
or Leuteotropic hormone (LTH). 

Metabolic functions of the growth hormone: 

Growth hormone is responsible for various general metabolic 
functions. It affects the diverse spectrum of integrated metabolic reactions, 
which participate in the overall process of growth. Growth hormone 
influences carbohydrate, protein and lipid metabolism. Growth hormone 
stimulates both the formation of cartilage (Chondrogenesis) as well as bone 
(Osteogenesis). It causes the retention of minerals such as nitrogen, 
potassium, phosphorus, sodium, etc useful for growth. 



64 



Deficiency of growth hormone or hyposecretion in children results in 
retarded growth. The premature arrest of skeletal development causes 
dwarfism. The adult dwarfs will grow to a height of only 0.9 to 1.2 meter. 
They never attain puberty or do not develop secondary sexual characters. 

Excessive secretion of GH results in over growth of the skeletal 
structures and the person may reach a height of 7 to 9 feet 
(gigantism). The excessive GH in adults also results in the increase in 
thickness of lower jaw and disproportionate over growth of bones of the 
face, hands and feet. The above condition is known as acromegaly. 

Thyrotrophic hormone or thyroid stimulating hormone (TSH): 

TSH is a glycoprotein with a molecular weight of 28,000 daltons. It 
is made up of 211 amino acids. The specific target organ for the TSH is the 
thyroid gland. It stimulates the thyroid to secrete the thyroxine. There exists 
a negative feedback mechanism between the circulating level of thyroxine 
and the hypothalamic releasing factor. When the thyroxione is less in blood, 
the hypothalamus produces more TSH releasing factor which on reaching 
the pituitary stimulates secretion of TSH. TSH on reaching the thyroid, 
stimulates the thyroid to secrete more hormone. Conversely, when there is 
excess thyroxine in the blood, the production of thyroxine is 
controlled by non- secretion of releasing factor from the hypothalamus. 

hypothalamus 

TSH releasing factor i 

■thyroxine 




pituitary f- 

■ thyroid 

Fig.1.22. Negative feedback mechanisms of TSH 
Adreno cortico trophic hormone (ACTH) : 

It is a protein hormone. ACTH also functions by the negative feed 
back mechanism and stimulates the adrenal cortex and its secretion. Its other 

65 



functions include the stimulation of formation of melanin pigments in the 
melanocytes of the skin, stimulation of insulin secretion and mobilization of 
fats from adipose tissue. 

Follicle stimulating hormone (FSH): 

It is a gonadotropic hormone that directly stimulates the gonadal func- 
tions in both males and females. The human FSH is a small glyco 
protein. The target organs for FSH in the females are the ovaries. It 
promotes the growth of graffian follicles and thereby increases the total weight 
of the ovary. It also promotes the secretion of oestrogen. In males, the target 
organs for FSH are the testes. It directly stimulates the germinal epithelium 
of the seminiferous tubules and augment the rate of spermatogenesis. 

Leutinizing hormone or Interstitial cells stimulating hormone (LH or 
ICSH): 

Human ICSH or LH is a glycoprotein. In females, the LH stimulates 
the ripening of ovarian follicles and induces ovulation. In males, the LH or 
ICSH, specifically affects the leydig cells or interstitial cells of the testes and 
stimulates the synthesis and secretion of the male hormone (Androgen) 
testosterone. 

Prolactin or Luteotropic hormone (LTH): 

Prolactin is called by several names such as luteotropin, luteotrophic 
hormone, lactogenic hormone, mammotropin etc. It is a protein hormone. Its 
main function is stimulation of milk formation or initiation of lactation 
following parturition in mammals. It also stimulates the corpus luteum to 
secrete the progesterone. Prolactin together with estrogen stimulates the 
growth of mammary glands and makes it ready for milk secretion. 

Hormones of Neurohypophysis: 

The neurohypophysis or the posterior pituitary secretes oxytocin and 
vasopressin. Oxytocin contains a sequence of amino acid residues. The term 
oxytocin refers to rapid birth. This hormone directly stimulates the smooth 
muscles of uterus and causes the contraction, and helps in the delivery of 
foetus. Another major physiological role of oxytocin is the secretion of milk 
from the lactating breast. Oxytocin stimulates the myoepithelial cells, which 

66 



surround the alveoli and ducts of mammary gland. The contraction of 
myoepithelial elements in turn expels the milk from the alveoli of the breast 
into the larger ducts or sinuses. From the sinuses, the milk is ejected out. 

The vasopressin: 

It is otherwise called as the antidiuretic hormone(ADH). Its main 
function is the retention of water inside the body by acting on the renal 
tubules. ADH increases the permeability of the distal tubules and collecting 
ducts and promotes the reabsorption of water from the renal filtrate. It causes 
the constriction of all blood vessels and increases the blood pressure. It also 
helps in the retention of urea. ADH deficiency leads to Diabetes insipidus. 
The symptoms of Diabetes insipidus are excretion of large volumes of dilute 
urine (polyurea), combined with an intense thirst leading to the consumption 
of large quantities of liquids (polydipsia). 

Thyroid gland and thyroxine 

Thyroid gland consists of a pair of lobes, which lie one on either side 
of larynx in the neck region. The paired lobes are joined by a narrow ante- 
rior bridge of glandular tissue called Isthmus of the thyroid. The lobes of 
thyroid in turn are divided into many lobules. The lobules consist of follicles. 
The follicles are called acini (acinus - singular). Each acinus is lined with 
glandular cubical epithelial cells. The cavity of acinus is filled with a 
gelatinous material called colloid, which contains the thyroxine. The hormone 
thyroxine is an iodinated hormone. It contains 65% iodine. The amino acid 
residue in thyroxine is tyrosine. 




lobe 



isthumus 



Fig.1.23. Thyroid gland 



Functions of thyroid: 

Thyroxine stimulates normal growth and development, especially the 
skeletal and nervous systems. It controls the rate of cellular oxidation and 
increases the basal metabolic rate. The basal metabolic rate (BMR) is 
defined as the amount of heat produced in the body in a given time, in 
complete state of physical and mental rest at 20°C room temperature. 

Actions of thyroxine: 

(i) This hormone is very essential for the development of nervous 
system particularly at the time of birth and during the first year, (ii) This 
hormone increases the metabolism of all tissues except brain, gonads and 
accessory sex organs, lymph nodes, spleen and lungs, (iii) The most 
important function is to increase the absorption of glucose from the small 
intestine, (iv) This hormone reduces serum cholesterol level, (v) It promotes 
protein anabolism, and helps in growth, (vi) It increases heart beat rate, force 
of contraction and pulse pressure, (vii) Presence of optimum level of 
thyroxine in the blood maintains efficient muscle functions and (viii) The 
optimum level of thyroxine in the blood is also necessary for normal gonadal 
function. 

Hypothyroidism: 

The physiological effect due to deficiency of thyroid hormone is 
referred to as hypothyroidism. It is manifested by iodine deficiency and simple 
goiter, cretinism and myxoedema. If the dietary intake of iodine becomes 
inadequate (below 10 micro grams per day) the synthesis of thyroxine is 
impaired. As a result, the thyroxine level falls in circulation and secretion of 
TSH increases, causing the hypertrophy of thyroid gland as a consequence. 
The thyroid enlarges to enormous proportions. This is called simple goiter. 
This condition is also called endemic goiter. It is caused due to lack of iodine 
in the soils of different regions of the world. 

Cretinism: 

Cretinism is found in children who are deficient of thyroxine hormone 
from the time of birth. The characteristics of cretinism are, retardation of 
mental growth to extreme degree, dwarf stature, protruding tongue and 

68 



abdomen, low basal metabolic rate, subnormal body temperature, 
retardation in skeletal growth and arrest of pubertal sexual maturity etc. 

Myxoedema: 

Myxoedema in adults, is a syndrome with the following 
characteristics viz., low BMR, dry, coarse, scaly skin, puffy and bloated 
face, coarse and sparse hair, hoarse voice, slow speech, slow thought 
processes, poor memory, etc. Other symptoms are muscular weakness and 
fatigue, low blood pressure, anaemia with increased serum cholesterol, etc. 

Hyperthyroidism or thyrotoxicosis (Grave's disease or exophthalmic 
goiter): 

The hyper function of thyroid gland results in Grave's disease. Grave's 
disease is characterized by increased BMR with increased pulmonary 
ventilation, protrusion of eye balls from the sockets (exophthalmas), increased 
heart beat rate, nervousness, emotional instability, weight loss, increased blood 
glucose and decreased serum cholesterol, derangement of sexual function 
etc. 

Parathyroid gland 

In man the parathyroid glands are small oval yellow-brown bodies 
found attached to the posterior surface of the thyroid gland. The parathyroid 
glands secrete two hormones namely, 1 . Parathormone and 2. Calcitonin. 

Parathormone: 

Purified parathormone is a simple polypeptide chain. It has short 
duration of biological activity. The half-life of the hormone is of about 20-30 
minutes only. 

Physiological effects of Parathormone: 

Parathormone manifests its regulatory effects at three different loci in 
the body namely the skeleton, kidneys and the gastro intestinal tract. In 
skeleton, the hormone directly acts upon the bone tissue to stimulate the 
activity of osteoclast cells (bone destroying cells) . Under the influence of this 
hormone calcium is released from the bone matrix into the circulation. As a 
result plasma calcium level increases. Thus it helps in the skeletal 
remodelling. 

69 



In kidney, parathormone induces a marked increase in phosphate 
excretion. In the gastro intestinal tract, parathormone stimulates the 
absorption of calcium and phosphate from the gut by enhancing the 
vitamin D synthesis. As a result, more phosphate and calcium are 
transported into the blood stream. Its other physiological effects include its 
inhibitory action over the osteoblasts or bone forming cells, bicarbonate 
reabsorption and reduction of urine pH, etc. 

Calcitonin: 

It is a calcium- lowering hormone secreted by the parafollicular cells 
of the parathyroid gland. It is a protein. Its physiological effects are antagonistic 
to that of parathormone. It inhibits bone resorption. In kidney, it inhibits the 
reabsorption of calcium, phosphorus, sodium, potassium, magnesium and 
other ions. It decreases gastric HC1 secretion. It also decreases the insulin 
and glucagon secretion. 

Hyperparathyroidism 

It is a condition where there is an increased amount of parathyroid 
hormone in circulation. Excess secretion of parathormone brings about 
demineralization of the bones. The protein matrix of the bone is also 
absorbed. These changes result in bone cyst and the elevation of the calcium 
level in the blood. The latter causes calcification of kidneys, arteries, 
stomach and lungs. 

Hypoparathyroidism 

Removal of parathyroids causes the blood calcium levels to fall and 
results in tetany. Tetany is characterized by low serum calcium 
(Hypocalcemea), reduced urinary excretion of calcium and phosphate, 
neuromuscular hyperexcitability, spasms of muscles and cramps etc. 

Pancreas 

The endocrine part of the pancreas consists of specialized groups of 
cells known as Islets of Langerhans. These cells synthesize, store and 
secrete two hormones namely insulin and glucagon. There are two kinds of 
cells namely, alpha and beta cells. The alpha cells produce glucagon while 

70 



the beta cells secrete insulin. In addition to alpha and beta cells another type 
of cells called delta cells are present in human pancreas. According to some 
investigators the delta cells represent the transitional forms of the two cell 
types alpha and beta. 

Insulin: 

Insulin is a protein hormone or a polypeptide hormone with 5 1 amino 
acid residues. Human insulin has a molecular weight of 5,734 daltons. It 
consists of two chains A and B , which are linked together by disulphide bridges 
formed between two cystine residues. 

Physiological effects of Insulin: 

It decreases glucose level in the blood in three ways: 

a. It increases conversion of glucose into glycogen and deposition of it in 
liver and muscles. 

b. It increases the rate of oxidation of glucose in the tissues. 

c. It increases the rate of conversion of glucose into fat and facilitates its 
storage in adipose tissue. 

d. It also regulates the rate at which amino acids are catabolised into water 
and C0 2 . 

e. Moderately, it also regulates the gluconeogenesis in the liver. 

Thus, insulin reduces the glucose level in the blood (Hypoglycemia). 
If the insulin is not secreted sufficiently, the liver and the muscles are unable 
to convert the glucose into glycogen. As a result more glucose enters into the 
bloodstream raising the blood sugar level. This condition is called 
Hyperglycemia. The excess of glucose is eliminated along with the urine 
resulting in a disease called diabetes mellitus. A diabetic patient excretes 
large amount of urine (polyurea) and consumes excessive fluid 
(polydipsia). He always feels hungry and eats excessively (polyphagia). 
When insulin levels are low, fat catabolism is increased and fats are 
converted into glucose. This further increases blood glucose levels and 
results in the accumulation of ketone bodies (Ketosis). 



71 



Hyperglycemia 

The normal fasting blood glucose level is 70 to 110 mg/dl 
(dl = deciliter). This range is maintained under varying conditions of food 
intake, fasting or body exercise. After a carbohydrate meal the blood sugar 
may reach a peak level of about 1 40mg/dl. If such a high level is maintained 
for a prolonged time, the condition may be termed as hyperglycemia. 
Hyperglycemia over a long period may cause degenerative changes in several 
organs and systems leading to malfunctions and mortality. Elevated blood 
sugar level of 400 mg/dl or more, in a few days causes dehydration leading 
to coma and death. 

Hypoglycemia 

It means a low plasma glucose concentration. This concentration can 
drop to very low values during fasting. It is termed as fasting hypoglycemia. 
It may result due to excess of insulin or other physiological factors. There is 
no fixed level of blood sugar at which hypoglycemia occurs. 

Fasting hypoglycemia may show symptoms such as hunger, increased 
heart rate, tremulousness, weakness, nervousness and sweating. These are 
caused due to activities of the sympathetic nervous system. Other symptoms 
such as headache, confusion, uncoordination and slurred speech are due to 
availability of too little glucans to the brain. Serious brain defects such as 
convulsions (epilepsy) and coma can occur if the plasma glucose 
concentration goes low. 

Diabetes Mellitus 

The name 'diabetes' in Greek means 'syphon' or 'running through' . 

This term describes the enormity of urinary volume excreted by people suf- 
fering from this disease. A persistant hyperglycemia leads to 
diabetes mellitus. This disease can be due to a deficiency of insulin or to a 
hypo responsiveness to insulin. 

In type I (insulin dependent) diabetes, the hormone is completely 
or almost completely absent from the islets of Langerhans and the plasma. In 
type II (insulin-independent) diabetes, the hormone is often present in plasma 
at near normal or even above normal levels. 

72 



The type I is less common. It is due to the total or near total destruction 
of the pancreatic (3 cells. 

The type II is due to insulin resistance. The insulin target cells do not 
respond normally to the circulating insulin. This may result due to obesity, 
over-eating and lack of exercise. The insulin hyporesponsiveness can be 
corrected if the person reduces his or her caloric intake. Thus dietary control 
without any other therapy is frequently sufficient to eliminate the elevated 
blood glucose level of type II diabetics. An exercise programme is also 
useful, since it will help to increase the number of insulin receptors. 

Glucagon: 

Glucagon, secreted by the alpha cells of the pancreas is a polypeptide 
hormone with 29 amino acids residues. 

Physiological actions of glucagon: 

The major function of glucagon in the body is to elevate the blood 
glucose level by glycogenolysis in the liver. As it raises the blood sugar level 
it is also called as Hyperglycemic hormone. A second important function of 
glucagon is the gluconeogenesis in the liver in which amino acids are used as 
substrates. It promotes lipolysis and the release of fatty acids in the adipose 
tissues. The increased fatty acid oxidation leads to ketogenesis. Glucagon 
also stimulates the myocardial contractility. Glucagon exerts a direct effect 
upon the kidneys and accelerates the renal plasma flow and glomerular 
filtration rate. A proper balance between insulin and glucagon production is 
necessary to maintain proper blood glucose level. 

Adrenal gland 

The adrenal gland or supra renal gland is composed of an outer 
cortex and an inner medulla. The adrenal cortex forms the major portion of 
the total mass of tissue of adrenal gland. In adults three concentric zones are 
discernible within the cortex. 1. A thin outer most layer, the Zona 
glomerulosa, 2. A thick middle region, Zona fasciculata and 3. A 
relatively thick inner layer, the Zona reticularis. In man, the cells of zona 
fasciculata and zona reticularis act as a single unit, the main function of which 
is to form glucocorticoids and to a lesser extent androgens and possibly 

73 



oestrogens. The mineralocorticoid hormone, aldosterone is secreted by the 
cells of the zona glomerulosa. The enzymes necessary for its synthesis reside 
in the cells of the zona glomerulosa. All the adreno corticoid hormones are 
steroids. 

Action of glucocorticoids 

The major glucocorticoids are cortisone and certain closely related 
steroids. These hormones stimulate the production of glucose from 
non-carbohydrate sources such as fats and amino acids. Glucocorticoids 
also decrease glucose utilization by tissues in general. All these effects lead 
to increased blood glucose level. Cortisone also acts as an anti-inflammatory 
agent. 

Action of mineralocorticoids: 

The major effect is on the metabolism of sodium ions and indirectly 
potassium ions. The major mineralocorticoid hormone is Aldosterone. Its 
most important effect is to promote the resorption of sodium ions from the 
renal glomerular filtrate. Secondary effects of sodium retention are an 
increased chloride retention and a decreased potassium retention by the 
kidneys. The most important function of the adrenal cortex is its role in stress 
tolerance. 

Adrenal medulla: 

The medulla of adrenal gland differs both in morphology and 
physiology from the cortex portion. Both cortex and medulla are derived 
independently and from totally different tissues in the embryo. The adrenal 
medulla in the adult humans and other mammals is invested closely by the 
cortical tissue. The cells of the adrenal medulla are large ovoid and columnar 
in type and are grouped into clumps around the blood vessels. The 
hormones produced by adrenal medulla are 1 . Adrenalin or epinephrine 
and 2. Nor adrenalin or nor epinephrine. The two hormones belong to a 
group called catecholamines. The various physiological and biochemical 
actions of adrenalin or epinephrine are the following: 

1 . Adrenalin stimulates constriction of blood vessels supplying the intestine, 
kidneys, viscera and skin and causes dilation of blood vessels supplying 
skeletal and heart muscle. 

74 



2. It increases the rate, amplitude and frequency of the heart beat. 

3. It causes relaxation of the smooth muscles of the digestive tract and brings 
peristalsis to a halt 

4. It causes relaxation of the bronchi, dilation of the pupil, closure of 
sphincters and increases sweating 

5. It causes contraction of muscles associated with hair follicles and makes 
the hair "stand on end" and causes goose flesh 

6. It accelerates respiration and stimulates mental alertness 

7. It stimulates the breakdown of glycogen to glucose, thereby increasing 
oxygen consumption and heat production. 

8. Biochemically it releases the free fatty acids and increases blood glucose 
level. 

9. Adrenalin prepares an individual during emergency or stress situations. 
Hence it is called the fight, flight and fright hormone. 

Action of Nor adrenalin or Nor epinephrine: 

Nor adrenalin has certain effects similar to that of adrenalin. For 
example, both the hormones dilate the coronary vessels. However, nor 
epinephrine cause vaso constriction in most organs other than heart. It 
increases both the systolic and diastolic blood pressures. It exerts a weakly 
inhibitory action upon the contractile activity of smooth muscle in the gastro 
intestinal tract. However, it does not relax the smooth musculature of the 
pulmonary bronchioles. Nor epinephrine exerts very little effect upon 
carbohydrate metabolism and oxygen consumption. 

Gonads: 

Both testes and ovaries, in addition to their role as reproductive 
gamete producing organs, function as endocrine structures also. 

Testis 

The testis in males, in addition to the germinal epithelial cells, 
contains groups of epithelioid cells called the interstitial or ley dig cells. These 
cells constitute the endocrine tissue of the testis. The leydig cells secrete the 

75 



androgenic hormone testosterone. The androgens are C19 steroids. In the 
normal post pubertal males, the rate of secretion of testosterone ranges from 
4-9 mg per day. 

Action of testosterone: 

1. Testosterone causes embryonic development of male reproductive 
organs, 

2. It promotes the development of the secondary sexual characters of males, 
including physical development, hair distribution, masculine voice and male 
behaviour at puberty. 

Ovary 

The ovaries are paired, oblong in shape and situated in the pelvic 
portion of the abdominal cavity. It releases hormones such as oestrogen 
and progesterone. 

1. Oestrogen 

Under the influence of the FSH from the adenohypophysis, the ovum 
grows and becomes enclosed in the Graffian follicle. Associated cells of the 
follicle produce a steroid hormone called estrogen. The oestrogens are C18 
steroid compounds. It is responsible for the growth of female reproductive 
organs and for the appearance of secondary sexual characters. 

2. Progesterone: 

After the discharge of the ovum from the Graafian follicle and after 
fertilisation, the ruptured follicle cells form a new structure called corpus 
luteum. It produces the pregnancy hormone progesterone. Progesterone is 
also synthesized and secreted by the placenta during the later part of 
gestation. This hormone is a C-21 steroid compound. 

Progesterone is responsible for the premenstrual growth in the 
non-pregnant woman's uterus. The development of the placenta during 
pregnancy and the embedding of the fertilized ovum in the uterus 
(implantation). 



76 



3. Relaxin: 

The corpus luteum of the pregnant woman secretes another hormone, 
relaxin in addition to progesterone. Relaxin helps in relaxing the muscles and 
ligaments of pelvic organs during childbirth (parturition). 

Receptor Organs 

The survival of animals depends on their ability to compute all the 
information flowing from the environment and integrate them into meaningful 
instructions to the effector organs. Information relating to the external and 
internal environment can be gained only through the sensory receptor 
organs. These organs have specialized cells that can transform the stimuli 
falling on them, whether it is chemical, radiant, electrical or mechanical, into 
electrical signals and convey the same to the central nervous system. In the 
CNS the integration and coordination of the data happens. This ability of the 
sensory cells is known as transduction and the receptors are sometimes 
referred to as transducers. 

Eye 

The visual system gives information about size, shape, color, 
luminosity and movements of object in the external world. 



choroid 



ciliary body 

cornea 
pupil 
iris 




sclera 



retina 



Fig.1.24. V.S. of human eye 



77 



(a) Focusing Mechanism in the Human Eye 

Light rays entering the eye are redirected or refracted. Refraction 
occurs through three surface of the eye before the light reaches the retina. 
The first of the refracting surfaces is the cornea, then the front surface of the 
lens and finally the rear surface of the lens. 

Between the cornea and the lens is a colourless, watery fluid called 
aqueous humour. At the back of the eye between the lens and the retina is the 
vitreous humour made of a gelatinus mucoprotein. The humours are 
transparent so that transmissions of light through the cavities of the eye to the 
retina is not normally impeded. Human eye has a lens apparatus whose 
convexity can be adjusted for focusing near and distant objects. This ability 
of the eyes to focus objects at varying distances is called 
ACCOMMODATION. The accommodation is achieved due to suspensory 
ligament, ciliary muscle and ciliary body. 

ciliary ring 

ciliary body 
ciliary processes 



. retina 

—suspensory ligaments 







Fig. 1.25. Lens with ciliary muscles 

When a normal eye is looking at a distant object, the ciliary muscles is 
fully relaxed and parallel rays from the object come to focus on the retina. 
Hence a clear image is seen. When the object is brought close to the eye the 
refractive power of the eye is increased by the process of accommodation. 
The increase in refractive power is the result of an increase in the curvature 
of the anterior surface of the lens. This avoids the blurred image for a closer 
object. Similar accommodation happens for viewing a distant object by 
stretching the suspensory ligament attached to the lens. This act alters the 
contour of the lens. 

Photochemistry of Retinal visual Pigments 

Rhodopsin or Visual Purple is a puplish red photosensitive pigment 
present in the outer segment of the rods (120 million rods). It is made up of 

78 



protein portion, an opsin (scotopsin) combined with an aldehyde of vitamin 
A called Retinene 1 , which is referred to as a retino. On exposure to light, 
rhodopsin is bleached, ie., broken down to retinene and opsin, but is 
resynthesised in the dark. Some of the retinene recombines with scotopsin to 
form rhodopsin while some are reduced to vitamin A. The rods are extremely 
sensitive to light and are responsible for vision in dim light. This is called 
SCOTOPIC VISION. 



cone 



Fig.1.26. Rod 



rod 



Fig.l.27.cone cells 



Cones also contain visual pigments made up of retinene, combined 
with a protein opsin (photopsin). Three pigments each responding to 
different wavelength are found in man. There are three primary colors namely 
red, green and blue. Color vision is a function of bright light vision and cones 
are responsible for color perceptions. In bright light maximum perception of 
colors is at the fovea region of the retina where rods are absent and only 
cones are present. In dim light when the rods in the extra foveal retina 
function, colors are not perceived and the various colors appear as shades 
of grey. Cones function in bright light and the system has more acuity and can 
perceive colors (PHOTOPIC VISION). 

Photochemical basis of retinal function is a basis of conversion of 
light energy into nerve impulses. It is this process that excites the nerve fibres 
and sets up nerve impulses. 

The impulses generated in the receptor neurons in response to 
generator potentials in the cones are interpreted by the brain as the 
appropriate intermediate colour. The interpretation or perception of colour 
pictures seen by our eyes is a complex function of the brain. It is located in 
the occipital lobe of the cerebral cortex. 

79 



The visual pathway 

The axons of ganglion cells pass through the eyeball at the posterior 
end and form the optic nerve which enters the cranial cavity. Therefore this 
region of the retina lacks receptors and is unable to perceive images which 
fall on it. This region is called optic disc and when charting the field of vision 
it is referred to as the blind spot. 

Errors of refraction 

In a normal eye focused for distant objects, parallel rays of light come 
to a sharp focus exactly on the retina. It can accommodate for clear vision of 
objects from infinity (far point) down to 25 cm (near point). This ideal 
refractive state is called emmetropia. A deviation from emmetropia is called 
ametropia. The important forms of ametropia are myopia, 
hypermetropia, astigmatism, presbiopia. Ametropia results from an 
imbalance between the length of the eye ball and its refractive power. 

(a) Myopia (Short Sightedness) 

Myopia results if the lens curvature is too great or the entire eyeball 
becomes elongated. Light rays entering the eye are refracted more than is 
necessary. Consequently light is focused in front of the retina. The image 
perceived is thus blurred. The condition is called short-sightedness as 
objects near the eye are clearer than those further away. Myopia can be 
corrected by placing a concave lens in front of the eye. The surface of the 
concave lens refracts light rays in such a way that the rays diverge slightly 
from their original path. The lens of the myopic eye now refracts the 
diverged light rays in to focus on the retina. 



_ r= _ a __ defect 



correction 





concave lens 
Fig.1.28. Myopia and its corrections 



80 



(b). Hypermetropia (Long Sightedness) 

Hypermetropia results when the curvature of the eye lens is not great 

enough. Light rays are not refracted enough and would thus be focused 

behind the retina. The condition is called long-sightedness because distant 

objects are clearer than near ones. This happens because light rays from 

distant objects require less refraction than rays from near objects. 

Correction of hypermetropia requires placing a convex lens in front of the 

eye. The lens converges light rays before they enter the eye so that the eye's 

focuses the light correctly on the retina. 

, . correction 

""-■• ..defect 





convex lens 
Fig.1.29. Hypermetropia and its corrections 



(c). Astigmatism 



Astigmatism occurs if either the cornea or lens is distorted. One part 
of the focusing mechanism then refracts light rays too much, or too less. 
Usually most of the images perceived is out of focus. Light rays from part of 
the object are focused in front of the retina, as in myopia. Rays from other 
parts would be focused behind the retina, as in hypermetropia. Astigmatism 
can be corrected by placing a lens in front of the eye. The curvature of this 
lens varies from one part to another to compensate for the eye's 
deficiencies. 

(d). Presbiopia 

This is the result of a reduction in the amplitude of accommodation 
with age due to hardening and loss of plasticity of the lens. Hence it becomes 
less capable of being moulded into a more complex form. Presbiopia begins 
at about 40 years of age. The remedy is convex lenses for reading. Any 
defect in the eye should be consulted immediately with the optometrist. 

Optometry 

The practice of assessing vision and establishing whether glasses or 
contact lenses are needed to correct any visual defect is known as 

81 



optometry. The eyes are examined by a qualified optometrist who will as- 
sess the errors of refraction, prescribe and supply glasses or contact lenses 
to correct it. Optometrists are not qualified to diagnose or treat disorders of 
the eye but will refer patients requiring further to an ophthalmologist. 

Retinopathy 

Retinopathy is the disease of the retina, usually resulting from either 
diabetes nielli tus or alternatively from persistent hypertension (high blood 
pressure). There are two types of retinopathy. 

(1). Diabetic retinopathy is characterized by tiny aneurysms (baloon like 
swellings) of the capillaries (tiny blood vessels) in the retina. New abnormal 
blood vessels which are fragile and bleed readily grow on the retinal surface. 
Haemorrhage into the vitreous humour may occur, fibrous tissues can also 
grow forward into vitreous humour. Treatment by laser surgery can often halt 
a progress of the conditon. 

(2). Hypertensive retinopathy is characterized by narrowing of the retinal 
arteries. Areas of the retina may be destroyed and causes haemorrhage and 
white deposits may also occur in the retina. It may even lead to retinal 
detachment. Remedy is laser treatment. 

Cataract 

Cataract is the opacity in the lens of the eye. The normal lens allows 
light to reach the retina when it becomes opaque and does not allow light to 
reach the retina, the person is unable to see clearly. Cataract is due to 
(coagulation) changes in the delicate protein fibres within the lens, cataract 
never causes complete blindness but causes increased loss of transparency. 
The clarity and the detail of the image is progressively lost. The front part of 
the lens becomes densely opaque and whiteness is visible in the pupil. 

The causes for cataract formation in the adult is related to aging, sun 
light exposure, smoking, poor nutrition, eye trauma, systematic diseases like 
diabetes mellitus, infection and injuries and certain medications such as 
steroids. Sometimes German measles in pregnant mothers causes cataract in 
the child. 

82 



To delay the onset of cataract one should have nourishing diet, 
protect eye from excessive exposure to sun rays, X-rays, intense heat and 
injuries. Diseases like diabetes and syphilis should be treated early and 
effectively. 

Two types of cataracts are dense nuclear cataract (cataract in the 
center of the lens) and Peripheral cataract (cataract in the periphery of the 
lens). There is no medical treatment for cataract. The only treatment is 
surgery. Once the cataract is removed, the eye is unable to focus, as there is 
no lens. So one has to use an artificial lens. This can either be glasses, 
contact lenses or insertion of introcular lenses. 

Today modern medical advances have made cataract surgery very 
successful. New surgical techniques and intracular lenses can restore 
excellent vision (97%). 

Lens Replacement 

For individuals who are over 40 years of age, considering refractive 
surgery to decrease dependence on glasses and contact lenses, Clear Lens 
Replacement (CLR) is an exciting option. In essence, this procedure entails 
removing the natural lens of the eye and replacing it with an intraocular lens 
(IOL) implant. 

CLR may be an excellent alternative to these procedures for people 
already wearing bifocals since CLR requires removal of the natural lens of 
the eye, the patient is subsequently unable to focus (accommodate) at near 
by objects . This is why CLR is best suited for patients over 40 who are 
already wearing bifocals. One potential solution to this problem of 
accommodative loss is implantation of the multifocal IOL (Intra Occular Lens) 
implant. This implant allows focusing at both near and far objects. 

Glaucoma 

Glaucoma is a serious disorder of the eye and is a common cause of 
blindness. Increased IOP (Increased Occular Pressure) compresses the 
optic nerve at the optic disc with degeneration of optic nerve fibres and 
cupping of the optic discs with progressive loss of visual acuity starting with 
peripheral vision. The retinal artery which enters the eye ball at the optic disc 

83 



is compressed causing retinal degeneration. In most cases the cause of 
glaucoma is unknown but in some cases it may be due to infection or trauma 
in the eye. When the IOP is very high (50-70 mm Hg) blindness occurs 
within few days. 

Nyctalopia 

Vitamin A is necessary for resynthesis of visual purple. Nyctalopia 
or night blindness is the first sign of vitamin A deficiency. Prolonged 
deficiency of vitamin. A leads to degenerative changes in rods and cones and 
nervous layers of the retina. Administration of vitamin A before degenerative 
changes occur will restore retinal functions. Normal retinal function also 
requires the presence of optimal amounts of other vitamins especially the B 
complex just as other nerve tissues do. 

Infections 

1. Stye : A stye is an acute infection of the glands located at the eyelid 
margin. There is swelling, pain, itching and redness in a small area at the lid 
margin. Treatment consists of using frequent warm compresses on the eye. 

2. Conjunctivitis: Infection in the conjuctiva is called conjunctivitis. Due to 
the infection the invisible blood vessels within the conjunctiva become 
engorged. Inflammation of the conjuctiva causes redness, discomfort and a 
discharge from the affected eye. The most common causes for 
conjunctivitis are infections (in children) and allergy (in adults). 

2a. Infective conjunctivitis : Most conjunctival infection are caused by 
bacteria (e.g staphylococci) and are spread by hand-to-eye contact or by 
viruses associated with a cold, sore throat, or illness such as measles, viral 
conjunctivitis sometimes occurs in epidemics, spreading rapidly through 
schools and other groups. 

2b. Allergic conjunctivitis : An allergic response of the conjunctive may be 
provoked by a variety of substances including cosmetics (mascara), 
contact lens cleaning solution and pollen. 

Symptoms : All types of conjunctivitis cause redness, irritation, 
itching, discharge and occasionally photophobia (abnormal sensitivity to bright 

84 



light). In infective conjunctivitis the discharge contains pus and may cause 
the eyelids to be stuck together in the morning. In allergy conjunctivitis the 
discharge is clear and the eyelids are often swollen. 

Treatment : Warm water is used to wash away the discharge and remove 
any crust on the eyelid. Infections are treated with eye drops or ointment 
containing an antibiotic drug. Allergic conjunctivitis may be relieved by 
use of eye drops containing an anti histamine drug. 

Eye care 

Eye is an important organ and it is to be taken care of. 

1 . Eye examination should be periodically done to determine the cause of 
visual disturbance or other symptoms relating to the eye. 

2. Foreign particles in the eye are very common and it may penetrate in the 
eye ball. So care should be taken while removing the dust to avoid damage. 

3. The retina should be periodically examined to assess conditions such as 
hypertensive retinopathy for hypertension and diabetic patients. 

4. Self medication should be avoided. A doctor should be consulted immediatly 
if there is any sudden pain or blurry vision. 

EAR 

Our ears provide us with two vital but very different senses : hearing 
and balance. Sound detected by the ears provides essential information about 
our external sourounding and allow us to communicate. In addition our ears 
contribute to our sense of balance to maintain upright posture and move 
without falling over. 

Sound is the sensation produced by longitudinal vibrations in the 
external environment. Loudness of sound is correlated with amplitude of sound 
wave and pitch with frequency (No. of waves / unit time). Audible 
frequencies to humans is in the range 20 - 20,000 cycles per second (cps, 
Hz). Only the young people are able to hear this full range. 

Sound perception depends on the loudness as well as frequency. 
The human ear is most sensitive to 50 - 5000 Hz range. But most sounds we 
normally hear fall within 500 - 5000 Hz. Since the human ear can 

85 



differentiate a wide range of sound energy (the loudest noise perceived is 
approximately 10 12 times more intense than the softest whisper) the decibel 
(dB) scale is used to measure the intensity of sound. 

Our ability to hear depends on a complex series of events that occur 
in the ear. Sound waves in the air are transmitted as vibrations through a 
series of structures to the receptor for hearing. The physical vibrations are 
detected and converted into electrical signals. Nerves carry the electrical 
signals to the brain where they are interpreted. The interpreted messages 
allow us to perceive the subtleties of sounds such as speech and music. 

Mechanism of hearing 

Functions of External Ear :- Sound waves enter the external auditory 
meatus, pass along the external eustachian canal and fall on the tympanic 
membrane (TM). This causes the TM to vibrate. 

Functions of Middle Ear :- The middle ear is an air filled cavity in the 
temporal bone which opens via the eustachian tube into the nasopharynx. 
The auditory tube opens during chewing, swallowing and yawning thus keep- 
ing the pressures on both sides of the tympanic membrane equal. 

The three auditory ossicles are localised in the middle ear. Of these, 
the malleus is attached to the TM, and the stapes to the membranous oval 
window on the medial wall. Incus articulates with these two bones. Thus 
vibrations of the TM are transmitted to the oval window. As the TM has an 
area of 90mm 2 and the foot plate of the stapes 3 .2mm 2 and the lever system 

formed by the ossicles multiplies the force 1 .3 times. 

perilymph 

scala tympani 



ear ossicles 



tympanam 



round window 




scala vestibuli 



i)J| scala media 



cochlea 
eustachian tube 



Fig.1.30. Internal structure of Ear 

86 



The vibrations of the oval window generate pressure waves in the 
fluid filling the vestibular canal. The pressure waves pass to the median canal 
and vibrate the basilar membrane. The tympanic canal is connected to a 
circular membrane called the round window just beneath the oval window. 
This arragement allows the pressure waves to transmit through the cochlear 
fluid. 

Functions of Cochlea :- The inner ear (labyrinth) is made up of the 
cochlea and the vestibule. The cochlear portion of the labyrinth is a tubule 
coiled 2.75 times. Throughout its length the cochlea is divided into three 
compartments by the basilar and the Reissner's membranes. The middle 
compartment (scala media) contains endolymph and the other two (scala 
vestibuli & scala tympani) contain perilymph. 

Organ of Corti : 

Located on the basilar membrane is the Organ of Corti which 
contains the auditory receptors . Four rows of hair cells arise from the basilar 
membrane. 



reissner's membrane 
scala media 
tectorial membrane 
scala vestibuli 
organ of corti 

scala tympani 




auditiory nerve 




basilar membrane 



Fig.l.31.CS of Cochlea 



Fig.1.32. Organ of Corti 



Stimulation of hair cells :- Movements of the foot plate of the stapes set 
up a series of waves in the perilymph of the scala vestibuli. This in turn causes 
vibrations of the vestibular membrane and hence of the 
endolymph in the scala media. These waves deflect the Reissner's 
membrane and this in turn produces disturbances in the basilar 
membrane which bend the hairs of hair cells in the organ of Corti. This leads 
to development of action potentials in the related nerve fibres which are 
transmitted along the auditory nerve. 

87 



The site of maximum distortion in the organ of Corti is 
determined by the frequency of sound, for high pitched sounds the 
maximum height of the waves is near the base of the cochlea and for low 
pitched near the apex. The extent of distortion is determined by the loudness 
of the sound. Interpretation of these impulses is made in the auditory cortex. 

Sound waves — > vibrate tymphanic membrane — > movements in ear ossicle 
chain — » vibration of oval window —> waves in perilymph (scala vestibuli) — > 
waves in endolymph — > deflection in the Reissner's membrane — » basilar 
membrane disturbed — > bending of hair cells — > action potential —> 
transmission by auditory nerve. 

Defects of the ear 

Several defects of the ear lead to hearing loss or even deafness. 
Hearing loss, or hearing impairment, happens when there is a problem with 
one or more parts of the ear or ears. 

Types of Hearing Loss :- There are a few different types of hearing loss: 
conductive, sensory, mixed (conductive and sensory combined), and neural. 

Conductive hearing loss:- This happens when there is a problem with a 
part of the outer or middle ear. Most kids with conductive hearing loss have 
a mild hearing loss and it is usually temporary because in most cases medical 
treatment can help. 

Sensory hearing loss :- This happens when the cochlea is not working 
correctly because the tiny hair cells are damaged or destroyed. 
Depending on the loss, a person may be able to hear most sounds (although 
they would be muffled); only some sounds; or no sounds at all. Sensory 
hearing impairment is almost always permanent and the ability to talk 
normally may be affected. 

Neural hearing loss:- This happens when there is a problem with the 
connection from the cochlea to the brain. 

The hearing loss may be congenital or due to middle ear fluid, serious 
infections, such as meningitis, head injury, listening to very loud music, 
especially through headphones, repeated exposure to loud sounds, such as 
machinery. 

88 



One of the common causes of conductive hearing loss is blockade of 
the external auditory meatus with wax secreted from ceruminous glands in 
the skin lining the meatus. In some people wax accumulates in the meatus 
and hardens, sometimes pressing against the eardrum. Normal hearing is 
usually restored after the hardened wax is removed with a special syringe. 

Another cause of conductive hearing loss, is a perforated eardrum. 
Perforation can be caused by infection in the middle ear or by 
mechanical injury resulting from a nearby explosion or a sudden blow to the 
head. Injury to the head can also cause the ossicles of the middle ear to 
become disconnected from one another, thus breaking the 
conductive path to the cochlea. 

Malfunction of the cochlea and acoustic nerve can be the cause of 
hearing loss, even though vibrations are conducted perfectly into the inner 
ear. Such hearing loss is called sensorineural (perceptive) hearing loss. 
Acquired forms of this condition can result from infection, head injury, blast 
from explosions or exposure to excessive noise. 

Hearing Aid 

Patients with a conductive defect which does not respond fully to 
treatment may be helped with a hearing aid. 



volume control wheel 




speaker 
amplifier 
microphone 

Fig. 1.33. Hearing aid 

A hearing aid is an electronic, battery-operated device that 
amplifies and changes sound to allow for improved communication. Hearing 
aids receive sound through a tiny microphone, which then 
converts the sound waves to electrical signals. The amplifier increases the 
loudness of the signals and then sends the sound to the ear through a speaker 
in an ear piece which fits into an outer ear canal. The electric signals are 
converted back to sound waves. 

89 



A volume control on the aid usually operated by turning a tiny wheel 
enables the level of incoming sound to be adjusted. 

More powerful aids that amplify sound to a greater 
degree are available. In these aids the microphone, amplifier and 
battery are contained in a larger case worn on the body; the currents is 
carried to the ear piece by a thin wire. Some people with conductive 
deafness especially if there is an infection or discharge in the ear canal may 
be given a bone condution hearing aid. This type of hearing aid may be fitted 
to a glass frame or hair band. 

Other devices available for the hard-of-hearing include 
amplified telephone receivers, flashing lights instead of door bells and 
telephone bells, vibrators that respond to sound, head phone for 
television sets, teletype writers and guide dogs for the deaf. 

Noise pollution 

The term noise is derived from the Latin word Nausea refering to the 
feeling of sickness in the stomach with an urge to vomit. Any unpleasant and 
unwanted sound is considered as noise. It is one form of pollution. Noise 
pollution can be defined as unwanted or offensive sounds that unreasonably 
intrude into our daily activities. It is responsible for various adverse effects. 
In recent years noise is recognized as a major pollutant on par with other 
chemical pollutants of air, water and biosphere. Noise has many harmful 
effects on man and the damage incurred is irreversible. 

There are various sources of noises and the sources are broadly 
classified into industrial sources and non industrial sources. The noise dumped 
into the atmosphere by the industires due to the functioning of machineries 
form the industrial sources. On the other hand the noise associated with 
urban development; road, air and rail transport; loud speakers, radio and 
television stations, construction sites, neighbourhood and recreational noise 
levels, and activities associated with urban living generally lead to increased 
noise levels. 

Sound is measured by several complex systems. The best known 
unit of measurement is the measurement of sound in decibel which is named 
after Sir Alfred Bell. The industrial noise survey of India recognized noise 
levels from 81dB to 120dB as permissible levels. 

90 



Loud noises (above 130 dB) can cause immediate and permanent 
damage to the muscles in the middle ear, altering the stiffness of the ossicles, 
damaging the hair cells of the cochlea and casuing the rupture of ear drum 
thereby reducing the efficiency of hearing. 

Prolonged exposure to unpleasant noises may lead to severe mental 
distubances and violent behaviour. Noise is also partially responsible for the 
increased consumption of alcohol, drugs, tranquilizers and sleeping pills. Noise 
pollution further contributes to a few cardiovascular problems. Peptic ulcers 
and asthma are aggravated. Small vessels to glomerular circulation are 
subjected to vaso constriction and ultimately the output of urine is reduced. 
Persons exposed to excessive noise at work place have temporary 
impairment of hearing. 

Skin 

The skin is a major organ of the body forming 8% of its total mass 
and having an area between 1 . 1-2. 2m 2 . It is the major interface between the 
body and the environment and covers the entire surface. It is continuous with 
mucosae at the various orifices and with lining tissue of organs like eyes and 
ears 

Various structures including sebaceous glands, sweat glands, hair 
follicles and nails are formed by modifications of epidermis. Sebaceous glands 
secrete an oily substance called sebum and open on the sides of the hair 
follicles. Sweat glands are of two types, Merocrine and Apocrine. Merocrine 
glands are found throughout the body opening on the surface and secreting a 
clear watery fluid. Apocrine glands are found in the regions like axilla, areola, 
pubis, scrotum and perianal regions. Their ducts may open on the surface or 
into the hair follicle. 

Dermis is made up of connective tissue consisting of matrix in which is 
embedded elastic and collagen fibres to give strength and elasticity. It also 
provides a compartment for blood vessels, lymphatics, nerves and cells 
associated with immunity. Receptors for the sensations such as touch, pain, 
pressure, warmth, cold and vibration senses are also found in the skin. 

Circulation through the skin serves two major functions nutrition and 
conduction of heat to the environment. 

91 



Functions of skin 

1 . Skin forms an effective barrier against infection by microbes. 

2. It prevents dehydration and provides defense against chemical, osmotic, 
thermal and photic damage. 

3. It limits and regulates heat loss. 

4. It provides a major sensory surface with a range of receptors. 

5. It has limited excretory and absorptive functions. 

6. Skin also helps in the formation of vitamin D. 

7. Its keratinization and high friction coefficient gives the skin a 
characteristic texture and helps in movement and handling of various 
substances. 

Melanin - functions 

Melanin is the brown black, non-haemoglobin-derived pigment 
normally present in the hair, skin choroid of the eye, meninges and adrenal 
medulla. It is synthesized in the melanocytes and dendritic cells, both of which 
are present in the basal cells of the epidermis. Melanin is stored in the form 
of cytoplasmic granules in the phagocytic cells called the melanophore, present 
in the under lying dermis. Melanocytes possess the enzyme tyrosinase 
necessary for the synthesis of melanin from the amino acid called tyrosine 

_, . tyrosinase , . , 
Tyrosine . . ^. Melanin 

Various disorders of melanin pigmentation cause generalized and 
localized hyperpigmentation and hypopigmentation. 

I. Generalized hyperpigmentation 

a) In Addison's disease, there is generalized hyperpigmentation of the skin, 
especially in areas exposed to light and buccal mucosa. 

b) Hyper pigmentation on skin of face, nipples and genitalia during pregnancy 
under the influence of oestrogen. 

c) In chronic arsenical poisoning, there is characteristic rain-drop pigmentation 
of the skin. 

92 



II. Generalized hypopigmentation 

Albinism is an extreme degree of generalized hypo pigmentation in 
which tyrosinase activity of the melanocytes is genetically defective and no 
melanin is formed. Albinoes have blonde hair, poor vision and severe 
photophobia. They are highly sensitive to sunlight. Chronic sun exposure 
may lead to pre-cancerous lesions, squamous and basal cell cancers of the 
skin. 

III. Localised hypopigmentation 

a) Leucoderma is a form of partial albinism and is an inherited disorder. 

b) Vitiligo is local hypopigmentation in the skin. 

c) Acquired local hypopigmentation can result from various causes such as 
leprosy, healing of wounds, radiation dermatitis, etc. 

Effects of solar radiation / UV radiation 

Invisible light forms a part of the electromagnetic spectrum 
immediately beyond the violet end of the visible light spectrum (i.e. between 
visible light and X-rays). Long wavelength ultraviolet light (i.e. that nearest 
visible light) is often termed as UVA; intermediate wavelength ultraviolet light 
is designated UVB; and short wavelength ultraviolet light (i.e. that nearest 
X-rays) is called UVC. 

The main source of UV radiation is the sunlight; others are UV lamps 
and welder' arcs. UV light penetrates the skin for a few millimeters only so 
that its effect is limited to epidermis. In human excessive exposure to UV 
rays can cause various forms of skin cancer such as squamous cell carcinoma, 
basal cell carcinoma and malignant melanoma. The efficiency of UV light as 
carcinogen depends upon the extent of light-absorbing protective melanin 
pigmetation of the skin. Fair skinned people and whites are more prone to 
skin complications due to UV exposure. People living close to the equator, 
outdoor workers and farmers in Tropics are exposed to light radiations. 

Skin grafting 

Skin grafting is a technique used in plastic surgery to repair areas of 
lost or damaged skin. Apiece of healthy skin is detached from one part of 
the body and transferred to the affected area. New cells grow from the graft 
and cover the damaged area with fresh skin. 

93 



Skin taken from an identical twin can be used for a graft, but skin from 
another person or an animal is soon rejected by the recipient body. A skin 
graft is performed because the area is too large to be repaired by stitching or 
because natural healing would result in scarring that might be ugly or restrict 
movement. 

Most grafts are performed by removing skin from the donor site and 
transferring to the recipient site. 

Dermatitis 

It is inflammation of the skin, sometimes due to an allergy but in many 
cases it occurs witout any known cause. Many types of dermatitis such as 
eczema are known. 

Contact dermatitis 

In this type of dermatitis the rash is a reaction to some substances 
that comes in contact with the skin. The reaction may result from a direct 
toxic effect of the substances or it may be an allergic response. Among the 
more common causes of the reaction are detergents, nickel (eg. in watch 
straps, bracelets, necklaces and fastening of underclothes), certain plants 
(eg. Rag weed), certain cosmetics and some medications in the form of 
creams, lotions or drops. The type of rash varies according to the substance 
causing it but it is often itchy and may flake or lister. Distribution of the rash 
corresponds to the skin area that has been in contact with the causative 
substance. 

Photo dermatitis 

This type of dermatitis occurs in people whose skin is abnormally 
sensitive to light. In the most common form of photo dermatitis a cluster of 
spots or blisters develop on any part of the body exposed to sun. 

Tongue 

In man the taste buds are found only in the mouth and are abundant in the 
tongue. They are distributed over the dorsal and under surface of of the tongue, 
on the laryngeal surface of the epiglottis, pharynx and on the cheek. 



94 




bitter 



sour 



sweet and salt 



Fig.1.34. Taste area of the tongue 

Each taste bud occupies the entire thickness of the epithelium. There is 
an opening on its free surface known as the pore canal. Taste buds are 
numerous at birth and their number decreases with age. 

Taste sensation and disribution of taste cells :- 

There are four primary or fundamental tastes. They are sweet, sour, salt 
and bitter. Alkaline and metallic taste are also sometimes included. 

Taste buds mediating the four primary taste are localized in certain 
regions on the tongue. The taste bud sensitive to bitter taste are at the back of 
the tongue. Those for sour tastes are on the lateral surface. Those mediating salt 
at the anterior part of the dorsum near the tip. The taste bud sensitive to sweet 
are near the tip. The taste bud in the palate respond to sour and bitter taste but 
have some sensitivity to sweet and salt. The pharynx and epiglottis are not 
sensitive to all four tastes. It is found that both sweet and salt are insensitive to 
taste in these regions. 

Mechanism of Stimulation 

Taste receptors are stimulated by substances in solution. The 
dissolved substances act on the microvilli of the taste receptors which project 
at the gustatory pore and sets up a generator potential to the receptor. This 
inturn activates the afferent nerve ending at the base of the receptor, 



95 



producing a propagated action potential in the nerve. The mechanism of 
production of generator potential varies in different receptors of taste. 

Excretion 

As a result of continuous synthesis and breakdown of materials many 
waste products are formed in cells. The process by which the cellular 
nitrogenous wastes are eliminated is called excretion. Three main nitrogenous 
wastes are ammonia, urea and uricacid. Various vertebrates excrete 
different form of nitrogenous wastes, according to the nature of their habitat 
and availability of water. 

Ureotelism 

Ureotelism is an adaptation for a semi -terrestrial habitat. Urea 
requires only a small quantity of water to form urine and never involves much 
water loss; Further, urea is much less toxic than ammonia and it can be 
retained in blood for sometime before it is transported and eliminated through 
the excretory organs. Though the concentration of urea in the blood is small, 
it can be stored safely in the bladder in high concentration. Thus ureotelism is 
conditioned by the shortage of water, characteristic of the terrestrial habitat. 

Urea Biosynthesis (Ornithine Cycle) 



Ammonia + CO2 + ATP — > Carbomyl phosphate 



Urea 





Ornithine 



Citrulline 

4 Aspartic acid 



Argino^succinic acid 



Liver is the principal organ of urea biosynthesis. In the ornithine cycle, 
ammonia, formed by deamination in cells and tissues, combines with carbon 
dioxide to form carbamyl phosphate. This compound is subjected to a cyclic 



96 



chemical reactions as provided in the figure. Three molecules of ATP are 
spent to convert the toxic ammonia into a molecule of urea. 

Nephron 

Nephron is the structural and functional unit of the kidney. There are 
about a million nephrons 

In general, the kidney performs the following vital functions in the 
body : 

1. Excretion of waste products resulting from protein metabolism. 

2. Regulation of acid-base balance by excretion of H + ions (acidification) 
and bicarbonate ions. 

3. Regulation of salt-water balance by hormones secreted both intra-and 
extra-renally. 

4. Formation of renin and erythropoietin and thereby playing a role in the 
regulation of blood pressure and erythropoises respectively. 

Mechanism of urine formation 

Urine is continually formed by each nephron and the processes 
involved in the formation of urine are 

1 . Glomerular ultra filtration, Tubular Reabsorption, Tubular Secretion 

Glomerular ultra filtration 

afferent arteriole J ^-^ ^- -^ _ efferent arteriole 

lomerulus 
Bowmann's capsule 




Fig.1.35. Malpighian capsule - Ultra filtration 

97 



Ultrafiltration of blood takes place in the malpighian body which acts 
as a biological filter. A malpighian body comprises Bowmann's capsule and 
glomeruli. 

Dynamics of filtration 

The kidneys normally receive an abundant blood supply of about 
1200ml/min or about 20 to 25 percent of the cardiac output. It flows through 
the capillaries of glomerulus where the blood pressure is comparatively high. 
The high blood pressure brings about effective filtration. The hydrostatic 
pressure (forward pressure 75mm/Hg.) of the blood in the afferent 
glomerular capillaries and the cumulative effect of the opposition pressures 
and renal intratubular pressure (lOmm/Hg.) play an important role in 
producing the glomerular filtrate. The hydrostatic pressure of the blood is 
always greater than the opposing pressures existing in the plasma protein 
and renal capillaries. Thus the available net filtering force (75-50mm/Hg. = 
25mm/Hg.) is chiefly responsible for glomerular filtration. The fluid in the 
capsule which is obtained by the process is termed glomerular filtrate. The 
volume of the glomerular filtrate produced each minute is called glomerular 
filtration rate (GFR). In man it is about 125ml/min. In 24 hours the total 
volume of glomerular filtrate is 170 to 1 80 liters. 

Tubular Reabsorption 

This is the second step in the urine formation. The glomerular filtrate 
contains many useful substances such as glucose, amino acids, mineral salts 
and vitamins dissolved in large amount of water. Reabsorption takes place in 
the uriniferous tubules. Reabsorption of useful substances is a differential or 
selective process. Substances such as glucose, sodium and calcium, are called 
"high threshold substance". They are actively reabsorbed in 
considerable quantities. Substances like urea and uric acid etc which are 
called "low threshold substances" are reabsorbed in small quantities by a 
simple diffusion process or passive reabsorption. Substances like creatinine 
are not reabsorbed. They are completely eliminated. 

Reabsorption in Proximal Convoluted Tubule 

Proximal convoluted tubule is responsible for the reabsorption of 
water, glucose, sodium phosphate and bicarbonates. The urine is found to 

98 



be isotonic in the proximal convoluted tubule. Isotonic condition of a 
solution indicates no passage of water across the membrane separating two 
such solutes. 



renal artery malpighian capsule 




->52^ ..- i ^ to £ i v~"^' 



renal vein 




Fig.1.36. Renal Tubular Absorpition 

Reabsorption in Henle's loop 

Urine becomes more and more hypertonic as it passes through the 
descending limb of the loop of Henle's. This is due to the fact that the thin 
descending portions of the Henles loop are freely permeable to sodium. As 
the urine slowly passes through the thick ascending limb of the loop of Henle, 
it becomes less hypertonic since the sodium is actively transported from the 
ascending limb to the descending limb through the interstitial tissue space. 



99 



Reabsorption in distal convoluted tubule 

On entering the distal convoluted tubule, the urine becomes nearly 
isotonic to the surrounding tissue fluid due to the active transport of sodium 
and passive transport of water. Summary of Renal Filtration and 
Reabsorption in 24 hours 

Reabsorption in collection tubule 

As urine (isotonic) passes into the collecting tubule it becomes once 
more hypertonic by the osmotic reabsorption of water under the 
influence of the hormone ADH. The release of ADH is controlled by the 
osmoreceptors in the hypothalamus in response to changes in the osmotic 
pressure of the plasma circulating through the collecting tubule. Thus the urine 
formed contains 96% of water, 2% urea and 2% of the metabolic products. 

A comparison of the amounts of various substances in 
24 hrs in the glomerular filtrate and excretion 



Substance 


Amount filtered 


Amount excreted in 




each day 


Urine each day 


Water 


1801trs 


l-21trs 


Protein 


2g 


O.lg 


Sodium 


580g 


5g 


Chloride 


640g 


6g 


Potassium 


30g 


2g 


Bicarbonate 


275g 





Glucose 


180g 





Urea 


53g 


25g 


Uric acid 


8.5g 


lg 


Creatinine 


1.6g 


1.6g 



Tubular Secretion 

This is the final step in the formation of urine during which the walls 
of tubule actively remove additional waste substances which are harmful to 
the body from the blood that have escaped filtration. 



100 



Renal Failure 

The reduction in the ability of the kidneys to filter waste products 
from the blood and excrete them in the urine is called as renal failure. The 
regulation of the water balance, salt balance and control of blood pressure 
are impaired due to kidney failure. The kidney failure also leads to uraemia 
(a built up of urea and waste products) and other chemical disturbances in 
the blood and tissues. This leads to various disorders and symptoms. 

Kidney failure can be acute (of sudden onset) or chronic 
(developing more gradually). In acute Kidney failure kidney function returns 
to normal once the causes have been discovered and treated. In chronic 
kidney failure the kidney function does not revive since it is caused by poor 
supply (flow) of blood, major illness, heart attack or pancreatitis. This 
damages the kidney tissue and its function. Heart transplantation is suggested 
for chronic type of failure. 

Dialysis 

Dialysis involves a technique used for removing waste products from 
the blood and excess fluid from the body as a treatment for kidney failure. 

Why it is done? 

The kidneys filter approximately 1 500 liters of blood daily. From this 
volume of blood, the kidney reabsorbs important elements such as sodium, 
potassium, calcium, amino acids, glucose and water. In people whose 
kidney have been damaged this process may fail either suddenly (in acute 
kidney failure) or gradually in chronic renal failure. Waste starts to 
accumulate in the blood, with harmful, sometimes even life threatening 
effects. In severe cases, the function must be taken over by artificial means 
of dialysis. Dialysis is called artificial kidney. 

Kidney Machines 

A kidney machine is a mechanical device through which a patient's 
blood passes. The blood leaves the body usually from an artery in the 
forearm and return to a nearby vein. Inside the machine the blood flows 
over or between membranes containing dissolved fluid (Dialysing fluid) and 
salt in concentrations normally found in blood. Solid constituents in the blood 

101 



inlet for dialysing fluid 




dialysing membrane 



^outlet 



Fig. 1.37. Artificial dialysis 

in excess of normal concentrations diffuse across the membrane into the 
dialyzing fluid. In this way waste like urea which accumulate in the body are 
extracted. Blood cells and protein remain in the blood. The process is called 
haemodialysis. 

Two kinds of dialysis are performed in clinical medicine. They are 
haemodialysis and peritoneal dialysis. 



Kidney stone (Calculus) 



/ 




kidney 



urinary bladder 
bladder stone 




Fig.1.38. Excretory system 



Fig.1.39. Stones in the bladder 



Stone formation in the kidneys, Ureters or Bladder, is caused by the 
precipitation from the solution of the substances in urine. Kidney and Ureter 
stones are more common than Bladder stones. The incidence of stone 
formation is highest in summer months as the urine is more concentrated due 
the loss of fluid in the sweat. The stones tend to be a recurrent problem. 
Chronic dehydration is the main cause for kidney stones. Kidney stone 
consists mainly of calcium oxalate and/or phosphate. 

102 



Stone consists mainly of uric acid and may occur in people with GOUT. 

Bladder stone usually develops as a result of a diet that is low in 
phosphate and protein. The most common symptom of a stone in the kidney 
or ureter is renal cholic (a severe pain) and the symptom for the bladder 
stones manifest with difficulty in passing urine. Stones in the bladder and 
lower ureter can be crushed and removed by cystoscopy or by 
ureterorenoscopy. The first line of treatment is lithotripsy which 
disintegrates stones by focusing shock waves on them from outside the body. 

Kidney transplantation 

Kidney transplantation refers to an operation in which a diseased 
kidney is replaced by a transplanted healthy kidney, either from a living 
donor or from a person who has just died (cadaver). One healthy donor 
kidney is sufficient to maintain the health of the recipient. 

Factors in improving the results of transplant surgery are 

( 1) To prevent rejection, effective immune suppressant drug treatment is given. 

(2) Tissue typing is necessary to help in matching recipient and donor tissue 
for transplant surgery thus minimizing the risk of rejection of a donor organ 
by the recipient's immune system. 

(3) After removal of organ from the donor it should be washed with an 
oxygenated fluid and cooled. This reduces the risk of damage. 

Diabetes mellitus 

Diabetes mellitus is the metabolic disorder of carbohydrate 
metabolism caused by insufficient or nil production of the hormone insulin 
by the pancreas. Insulin is responsible for the absorption of glucose into 
cells for their energy needs and into the liver and fat cells for storage as 
glycogen reserve. Insulin deficiency may be due to (1) pancreatic disorders 
(2) defects in the synthesis of insulin from Beta cells of Langerhans 
(in pancreas) (3) destruction of Beta cells and (4) genetic defects etc. 

Symptoms 

(1) The blood sugar level is more than 120mg. in diabetic patients. 

103 



(2) Untreated diabetes exhibits the following symptoms. 

(a) Polyurea - excretion of increased quantity of urine. 

(b) Polydipsia - excessive thirst leading to increased consumption of water. 

(c) Polyphagia - excessive appetite leads to increased in take of food. In 
spite of over eating, diabetic patient looses weight. 

(3) Weakness and body pain are the common symptoms. 

(4) The body's inability to store or use glucose causes weight loss, insatiable 
hunger and fatigue. 

(5) Diabetes mellitus also results in abnormal (fat) metabolism. 

(6) Accelerated degeneration of small blood vessels. 
Type's of diabetes mellitus 

(1) Insulin -dependent type. 

(2) Non-insulin dependent. 

Insulin-dependent type: This type develops due to heavy viral infection which 
reduces the production of insulin. 

Non-insulin dependent: This is due to inadequate amount of insulin 
production. Obesity (over weight) is the major reason. This type usually of 
gradual onset and develops mainly in people over 40. Recently insulin 
resistant diabetes is commonly noticed and reported in younger persons too. 

Causes for Diabetes 

(1) Diabetes tends to run in families so it occurs in people who inherit the 
genes responsible for the insulin dependent form. 

(2) Viral infection that damages the pancreas causing the deficiencyof insulin. 

(3) Obesity is the major cause leading to development of non insulin dependent 
diabetes. 

(4) Severe illness such as pancreatitis and thyrotoxicosis causes diabetes. 

(5) Intake of drugs like corticosteroid drugs and diuretic drugs. 



104 



The preventive measures comprise 

(1) Maintenance of normal body weight through adoption of healthy 
nutritional habits and physical exercise. 

(2) Correction of over nutrition and obesity may reduce the risk of diabetes 
and its complications. 

(3) Alcohol and smoking should be avoided. 

(4) Control of high blood pressure, elevated cholesterol and high triglyceride 
levels. 

(5) Susceptible persons can prevent diabetes by avoiding the risk factors. 

When diabetes is detected, it must be adequately treated.In order to 
maintain blood glucose levels within the normal limits one should maintain 
ideal body weight. It is achieved by balanced diet, physical exercise, frequent 
checking of blood sugar, blood pressure. Maintenance of body weight and 
visual acuity are some prognostic tips. 

Reproduction 

All living organism maintain their populations by reproduction. Most 
simple organisms such as bacteria reproduce asexually by cell division 
resulting in offspring's that are genetically identical. 

In human beings, reproduction is sexual, involving the fusion of two 
reproductive cells, namely a sperm (male gamete) and an egg (female ga- 
mete). If a sperm succeeds in fertilizing an egg, DNA (genetic material) from 
each parent combines to create a unique individual. Sexual reproduction re- 
sults in an infinite variety of offsprings. 

Functioning of male reproductive system 

The central role of the male reproductive system is carried out by the 
testes, which produce sex cells called spermatozoa or sperms containing 
genetic material. The testes produce sperms continuously from puberty onward. 
Men remain fertile for a much longer period than women. In addition, the testes 
manufactures male sex hormones or androgens which influence sperm 
production, fertility and sex drive. Male sex hormones also promote the 
secondary sexual characters. 

105 



Gametogenic function of testes 

Factors controlling spermatogenesis: FSH of pituitary gland 
stimulates and controls spermatogenesis. It acts on Sertoli cells to facilitate 
last stages of maturation of spermatids. It further stimulates the production of 
androgens such as testosterone. 

The LH of the pituitary acts on the Leydig's cells of the testes that 
releases testosterone. The temperature of testes should be maintained at 
32°C for an effective production of spermatozoa. 

Spermatozoa 

Each mature spermatozoan is a motile cell . It has an oval flat head 
having an acrosome and a large nucleus containing chromosomal material. The 
head is followed by a short neck, a body (middle piece) and a long tail. The 
middle piece contains spiral mitochondrial sheaths which are the site of energy 
production. The tail has a main piece and an end piece. The energy for movement 
is provided by ATP molecule. 

head 

nucleus 

middle piece 



• acrosome 

Fig.1.40. Spermatozoan structure 

Puberty 

Puberty is a process in sexual development. Once puberty is reached 
sperms are manufactured continuously in the two testes at a rate of about 1 25 
million each day. Puberty occurs between age 12-15 Hormones secreted by the 
pituitary cause levels of the male sex hormone testosterone to increase, 
stimulating changes such as general growth, and the development of secondary 
sexual characters. 

Transport of spermatozoa. For reproduction to take place, the sperm must be 
transported to the female reproductive system. The mature spermatozoa that are 
formed leave each testis through an epididymis, a long coiled tube that lies above 

106 





and behind each testis. The sperms are stored in the epididymis and periodically 
pushed into the vasdeferens the tube that connects an epididymis to an 
ejaculatory duct. During sexual activity each vas deferens, contracts and pushes 
the sperm toward urethra, the tube that connects the bladder to the outside of the 
body. The sperms are carried in a fluid consisting of secretions from various 
glands forming a thick seminal fluid or semen. 



seminal vesicle 

prostate gland 
vas deferens 



urethra 




testes 



Fig. 1.41. Male reproductive system 



Semen is a milky mucoid fluid which contains sperms (50 million in single 
ejaculate) plus seminal plasma made up of secretions of the seminal vesicles, 
prostate, Cowper's gland and bulbo - urethral glands. Semen provides nutrient 
that help to keep the sperm healthy and also serves as a medium for the 
spermatozoa to swim. 

During arousal, the penis gets enlarged and becomes firm. Muscular 
contraction at the have of the penis then forces the sperm through the male 
urethra into the vagina during male orgasm. 

Hormonal control: Male reproductive function is controlled by several 
hormones. 

1 . The hypothalamus of the brain controls the release of FSH and LH through 
its releasing factors. 

2. FSH and LH stimulate the gonads. Hence the gonads produce sperms 
and secrete the hormone, testosterone. 



107 



3. Testosterone controls further male reproductive functions. It also helps to 
develop and maintain secondary sexual characters, such as enlargement of 
larynx, deepening of voice, growth of hair and other adolescent changes. 

Regulation of testicular function 

The hypothalamus, anterior pituitary and testes are interrelated in 
testicular functions. FSH from the pituitary stimulates spermatogenesis in the 
presence of testosterone. High concentration of testosterone is maintained due 
to the presence of androgen binding protein which is secreted by the Sertoli cells . 
These cells also secrete another hormone called inhibitin which inhibits the action 
of testosterone. 

Testosterone secretion by Leydig cells is stimulated by LH. The 
testosterone has its action on different target cells. It diffuses into the seminiferous 
tubules and stimulates spermatogenesis and suppresses secretion of LH by acting 
on hypothalamus and anterior pituitary. 

Functioning of female reproductive system 

The central role of the female reproductive system is carried out by the 
ovaries. They produce sex cells called ova or eggs containing genetic material. 

By a process of fertilization an egg derives the potentiality to develop 
into a foetus. The ovaries also secrete female sex hormones that control sexual 
development and the menstrual cycle 




fallopian duct 



ovary 



vagina 



Fig.1.42. Female reproductive system 



108 



Endocrine function of Ovary (Female Sex Hormones) 

The ovaries produce the female sex hormones oestrogen and 
progesterone. The secretion of these hormones are controlled by follicle - 
stimulating hormone and lutenizing hormone which are produced by pituitary 
gland. Female sex hormones control sexual development at puberty, the 
menstrual cycle and fertility. 

Oestrogens 

These are steroidal hormones secreted by the theca interna of the ovum, 
cells of graffian follicle, corpus luteum and placenta. Oestrogen hormone 
controls the development of accessory sex organ and secondary sexual 
characters. It regulates menstrual cycle. Oestrogen promotes growth of ovarian 
follicles. Further it causes the growth of the breasts and formation of melanin 
pigments. 

Progesterone is the principal hormone secreted by the corpus luteum. It 
prepares the uterus for implantation of the fertilized ovum.lt helps in the 
formation of placenta and for maintaining pregnancy. Further during preguancy it 
inhibits contraction of uterus. It also suppresses ovulation and menstruation in 
pregnancy. 

Structure of a mature ovum 

Human ovum is small and contains no yolk (Alecithal egg) It is more than 
1 OOum in diameter At the time of ovulation, the ovum is surrounded by a striated 
membrane called zona radiata and later it is replaced by an unstriated membrane 
Zona pellucida (Primary egg membrane). 




follicle cell 
zona pellucida 

nucleus 

theca 
corona radiata 

Fig.1.43. Human ovum 



109 



The growing oocytes are surrounded by follicle cells. Some of the 
follicular cells of the ovary are found outside the zona pellucida and are termed 
as Corona radiata (Secondary egg membrane) which is peeled off when the 
oocyte passes down the oviduct. The follicles and the developing oocyte 
together constitute Graafian follicle. The whole surface of the graafian follicle is 
supported by theca interna and theca externa. 

Ovulation and fate of the ovum 

The shedding of the ovum from the ovary is called ovulation. The ovarian 
follicle enlarges and reaches the surface of the ovary. The stroma and the theca 
of the Graffian follicle ruptures and the ovum is shed from the ovary. As it reaches 



corpus luteum 



ovum or egg 




graafian follicle 



Fig.1.44. Ovulation 



the fallopian tube it may get fertilized. The fertilized egg reaches the uterus and 
gets implanted on its wall. If the ovum is not fertilized in the fallopian tube it dies 
in 12- 24 hours. 

Corpus luteum 

The corpus luteum is an important structure needed at the time of 
pregnancy. It is derived from the empty graafian follicle after ovulation. The 
corpus luteum secretes a hormone called progesterone. It is a steroid hormone, 
secreted in significant amounts by the corpus luteum and placenta. 

Menstrual cycle 

The functioning of the reproductive system in human adult female is 
characterized by the menstrual cycle. While the changes concerned within ovula- 
tion and the formation of the corpus luteum, are going on in the ovary, the uterine 

110 



endometrium shows striking cyclical changes. The rhythmical series of changes 
in the sex organs occur for about 28 days through out the reproductive life of 
women from puberty to menopause (except during times of pregnancy). It is 
called the menstrual cycle. 

The most prominent feature of this cycle is a monthly flow of blood from 
the genital canal. This is called menstruation or menses. A menstrual cycle begins 
with the onset of menstrual bleeding and ends just before the next menstruation. 
Bleeding Phase Bleeding Phase 



I 



1 



ffTTVh 



2 3 4 5 6 7 8 9 10 1112 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 1 2 3 4 5 
FSH 



OESTROGEN 
(PREDOMINANT) 

LH 



OESTROGEN (LESS) 
PROGESTERONE PREDOMIANT 



Folicular phase 



Luteal phase 



1 



Menstrual cycle. 



Fig.1.45. Menstrual cycle 



The menstrual cycle is usually divided into the following phases on 
the basis of changes taking place in the uterine endometrium. 

The follicular phase or Proliferative phase ( 5th day - 14th day) 

The follicular phase is initiated by the release of follicle stimulating 
hormone (FSH) from the anterior pituitary gland. During this phase, a 
primary follicle begins to enlarge. While it is growing, the follicles secrete 
oestrogen and smaller quantities of progesterone into the blood. Under the 
effects of oestrogen from the developing follicle, the endometrium starts 
regenerating from the basal portion. Deeper parts of the glands start 

111 



proliferating. By day 14, graffian follicle has matured and pushed up against 
the ovary surface. The secretion of FSH ceases at the end of follicular phase. 

The Luteal phase or Premenstrual phase (15th day - 28th day) 

The luteal phase begins at day 14. Under the influence of Leutenizing 
hormone (LH) released by the anterior pituitary, rupture of graffian follicle 
and release of ovum (ovulation) occurs. After ovulation, the empty follicle is 
transformed into a transitory endocrine gland called corpus luteum. The 
corpus luteum slowly increases in size and releases a large quantity of 
progestrone and smaller amount of oestrogen into the blood. The 
progesterone acts on endometrium of the uterus, preparing it to receive the 
fertilized ovum. To maintain pregnancy and to prevent the contraction of 
uterus, the progesterone hormone is highly essential. If there is no fertilisation, 
the corpus luteum degenerates and is reabsorbed by the ovary at the end of 
luteal phase. 

The menstrual phase (1st - 5th day) 

The decline in progesterone and oestrogen initiates shedding of the 
endometrium and severe bleeding in a process called mensus or 
menstruation. During this phase, all the extra layers are sloughed off along 
with unfertilized egg. At the termination of menstruation, the corpus luteum is 
converted into a scar tissue called corpus albicans. 

Fertilization 

The union of the egg and the sperm is called fertilization. It results in 
the production of a single diploid cell called zygote. 

At the time of ovulation, the ovum is fully matured and it enters the 
infundibulum of the uterine tube and passes into the ampulla. Fertilization of 
the ovum occurs in the ampulla of the uterine tube. One spermatozoan pierces 
the egg membrane, zona pellucida and enters the ovum. Polygamy (entry of 
more sperms) is avoided by the formation of fertilization membrane around 
the ovum. 

In vitro fertilization (Test tube babies) 

The so called test tube babies are produced by the technique of in 
vitro fertilization. (In vitro = outside the body, as against in vivo = within 

112 



the body). This technique is being increasingly used in couples who are not 
able to achieve fertilization in the normal way 

Gonadotropins are administered to the woman to stimulate growth 
of follicles in the ovary. Just before ovulation, the ovum is removed (using an 
aspirator) and is placed in a suitable medium. Spermatozoa are added to the 
medium. Fertilization and early development of the embryo takes place in 
this medium. 

The process is carefully monitored. When the embryo is at the 
8-celled stage, it is put inside the uterine endometrium. Successful 
implantation takes place in about 20 percent of such trials. The techniques 
are complex and need a team of well trained experienced personnel with 
high degree of skill. The success rate is only about 20% and 2 or 3 attempts 
may be necessary. It is also very expensive. The first success with this 
technique was achieved by Steptoe and Edwards of UK in 1978. However 
successful 'test tube babies' have been produced in many countries 
including India. 

Gamete Intra fallopian transfer (GIFT) 

It is a newer method in which the fertilized ova are introduced into 
the fallopian tube from where they naturally pass to the uterus for 
implantation. This method is considered to have a higher success rate than 
IVF. An even newer technique is the introduction of a single sperm into the 
ovum by microinjection. 

Birth control 

The population problem is assuming serious proportions in many 
developing countries. In India, the population which was about 400 million in 
1960 is now 100 crores or 1000 million. Realizing the dangers inherent in 
population growth, the government of India has taken several measures to 
check population growth and have given family welfare programmes an im- 
portant place in the five year plans. The World Health Organization (WHO) 
has also stressed the importance of family planning in the Global Strategy for 
Health for All by 2000 AD. 

The National Family Welfare programme is a comprehensive scheme 
which includes: 

113 



1 . Maternal and Child Health Care (MCH) 

2. Immunization of mothers, infants and children. 

3. Nutritional supplement to pregnant women and to children. 

4. Contraception with health education, to motivate couples to accept 
contraceptive methods and to adopt small family norms. 

Contraception : 

Contraception is the prevention of pregnancy resulting from coitus. 

A. Barrier Methods 

Prevents entry of sperms into vagina or uterus. 

(a) The Condom: The male wears a condom which covers the erect 
penis, and prevents deposition of sperms in the vagina. Condoms are made 
of rubber from latex. Ejaculated semen is retained within the condom 
preventing their entry into uterus. In India thin condoms called Nirodh, are 
manufactured and widely used. Condoms can be combined with spermicides 
inserted into the vagina. Condom also protects against sexually transmitted 
diseases (STD) like syphilis, AIDS. 






Fig.1.46. Condom Fig.1.47. Cervical caps 

(b) The Diaphragm (cervical cap): Women can wear a vaginal 
diaphragm fitting into the vagina or a cervical cap fitting over the cervix. 
They prevent entry of sperms into the uterus. They are made of synthetic 
rubber or plastic, and are used in combination with chemical spermicides. 

B. Hormonal Methods 

Hormones are prescribed spills, implants, or injections. Some 
hormonal contraceptives contain only progestin, which is a type of female 
hormone and some contain a combination of both {combined pill) 
progesterone and oestrogen and prevents ovulation. Hormonal methods are 

114 



nearly 99 percent effective. The effects of Hormonal method stops (interfere) 
the mechanism of ovulation. They can also stop the mechanism of conduction 
of ovum along the fallopian tubes. The hormones interfere in the thickening 
of the endometrium and they may also cause the formation of mucus in the 
cervix and vagina to prevent the penetration of sperms. 

C.Mechanical Methods 

The intrauterine device (IUD) and intrauterine system (IUS) are 

contraceptive devices inserted into the uterus. Copper-T is a synthetic T 

shaped device made up of copper and plastic (non irritant), is placed inside 

the uterus. This can remain for a period of 3 years. This also helps to give 

adequate time inerval between pregnancies. 

vas deferense 
fallopian tube 





5?W 



copper - 



uterus 




Fig.1.48. Copper-T Fig.1.49. Tubectomy Fig.1.50. Vasectomy 

D. Surgical Methods 

Surgical contraception, or sterilization, is an operation that makes a 
person infertile. This surgery can be carried out in men (vasectomy) and in 
women (tubectomy). 

Vasectomy is the method of permanent birth control in male in which 
the removal of a part of the vas deferens and ligations are performed. It is 
simple in all aspects. Male sterilization is not immediately effective. The seminal 
vesicles still contain sperm after the operation, and a condom must be used 
until semen analysis shows that no sperm are left. Tubectomy is the method 
of permanent birth control in female, here a portion of fallopian tube is cut of 
and the cut ends are ligated to prevent fertilization. Female sterilization is 
effective immediately, but the risk of ectopic pregnancy is slightly increased. 

115 



2. MICROBIOLOGY 

Introduction: 

The world of microorganisms includes various species of 
bacteria, viruses, fungi and protozoan parasites. The discovery of 
microscope and the ingenius techniques of isolation and identification of these 
microbial organisms opened up a new field of study named Microbiology. 
This study deals with the form, structure, reproduction, physiology, 
metabolism and classification of micro organisms. The area of 
microbiological studies include various aspects of their distribution in nature, 
their relationship to each other and to other organisms, their effects on plants, 
animals and human beings, their roles in the sustainability of environmental 
habitats such as soil, air and water and also their beneficial aspects to 
biotechnology. 

History of Medical microbiology: 

The medical microbiology had its origin in the year 1 888 when the 
Pasteur Institute in Paris (France) was established. Robert Koch 
became the Director of the Institute For Infective Diseases. Both Louis 
Pasteur and Robert Koch infused the spirit and interest to gain knowledge in 
medical microbiology to the countrymen of America and Europe. The 
medical microbiology deals with the aspects of infection, the causative agents 
of infection and the diseases due to infection. Following the establishment of 
Germ Theory of Diseases by Pasteur, innumerable infectious diseases that 
haunt the human population were discovered. For most of these infectious 
diseases, the drugs and vaccines have been found. 

Pasteur, Koch, Lister : 

Medical Microbiology involves the study of micro organisms that 
colonize or infect human beings; the mechanism by which they cause 
diseases; the body's response to infection and specific antimicrobial 
prevention and treatment. 



116 




Fig. 2.1. Louis pasteur 

The contribution of Louis pasteur (1822 - 1895) in France in the 
field of microbiology lead to a greater understanding of human ailments and 
animal diseases. Much of Pasteur's work involved the growth of bacteria 
and yeasts in liquid cultures. He developed methods of sterilization and of 
pasteurization. Pasteur (1857) observed different kind of microbes 
associated with different kinds of fermentation, e.g. Spheres of variable size 
(yeast cells) within alcohol fermentation and smaller rods (Lactobacilli) with 
lactic fermentation. This finding led Pasteur to state that specific microbe 
may cause specific disease in man. 

His crowning achievements were Pasteurisation of milk, the 
development of techniques to reduce the virulence of infectious organism, 
without eliminating their capacity to produce immunity. In this way he 
developed vaccines, for the control of "cholera" "anthrax" and "rabies" in 
man. 

Robert Koch - (1843 - 1910) 

Robert Koch, a younger contemporary of Pasteur, made his 
contributions on new procedures for staining, visualizing and growing 
bacteria. He solidified liquid culture media with agar. He also isolated and 
characterized the bacilli of anthrax, and tuberculosis and demonstrated their 
causative role by a series of experiments. 

After identifying the tubercle bacillus, Koch has advocated his 
postulate, in order to distinguish a pathogenic microbe from adventitious 
microbes. The impact of his work towards the end of 19th century lead to 
the discovery of "specific toxins" made by the causative bacteria for 
diphtheria and tetanus and "antibodies" produced in host animals against the 

117 



toxins to neutralise their effect. His finding also lead to immunization therapy. 
He was awarded the Nobel Prize in the year 1905 for his work on 
tuberculosis. 

Contributions of Joseph Lister : (1827 - 1912) to microbiology is the 
technique of "pure culture" of bacteria. The growth of a mass of cells of the 
same species in a laboratory vessel / test tube using serial dilutions in the 
liquid media is called pure culture. Lister obtained a pure culture of the 
organism Bacterium lactis and also found the importance of pure culture 
which form the suitable media for the growth of micro organisms, reponsible 
for infections, fermentation, nitrogen fixation in soil, etc. The pure culture 
techniques lead to developments in modern microbiology. 

On the basis on Pasteur's evidence, in 1860 Joseph Lister, 
discovered a system for "antiseptic" surgery. This system prevents the 
surgical wound infection and other lethal complications. 

I. Virus: Structure, Genetics, Culture and Diseases: 

Viruses are infectious agents. They are much smaller than the 
bacteria. Their approximate size ranges from 20 to 300 nm. Viruses are 
incapable of independent growth in artificial media. They can grow only in 
animal or plant cells or in microorganisms. Hence they are referred to as 
obligate intracellular parasites. They reproduce in these cells by replication. 
Replication is a process in which many copies or replicas of the viral 
component are assembled and made to represent the progeny. They lack 
metabolic machinery of their own to generate energy or to synthesize 
proteins. They depend on the host cells to carry out these vital functions. The 
bacterial viruses are called bacteriophages. These viruses infect the 
bacteria and multiply inside the bacterial body and cause the lysis of bacteria 
(lytic cycle) or integrate themselves with the bacterial genome (lysogeny). 

Structure of Viruses: 

Animal and plant viruses are composed of a central core of nucleic 
acids surrounded by a protein covering called capsid. The capsid is made up 
of units called capsomeres. Viruses exhibit a characteristic symmetry, 
1. Spherical viruses are isohedral, 2. Rod shaped viruses are helical in 
symmetry. Certain group of viruses are complex in symmetry. 

118 



Some animal viruses, in addition to the nucleocapsid structure 
contain an outer membrane like structure called the envelope. The envelope 
is made up of lipoproteins. The envelope conceals the symmetry of viruses. 
Virions with envelopes are sensitive to lipid solvents such as ether and 
chloroform. On the other hand, the naked virions are not affected by the 
lipid solvents. 

Isohedral viruses such as adeno viruses, SV15, polio viruses and 
blue tongued viruses are spherical in shape and their surface is a lattice with 
identical triangular units. 

Helical surface symmetry and structure are characteristic of tobacco 
mosaic virus(TMV) and animal viruses that cause diseases such as measles, 
mumps, influenza and rabies. In these, the nucleo capsid is a flexible 
structure packed within a fringed lipoprotein envelope. The fringes are made 
of glycoproteins. In TMV the nucleic acid core is covered by a capsid 
consisting of closely packed capsomeres arranged in a helix. 

Complex or uncertain symmetry is seen in Pox viruses, T-bacterioph- 
ages,. These have different proteins and lipoproteins. 



outer coat 



inner core 



Fig. 2.2. Morphology of viruses Fig 2 2(a) ^-bacteriophage 

Viral genetics: 

The viral genome contains all the genetic information either as DNA 
or RNA. but never both. The proportion of nucleic acid in a virion varies 
from 1 % as in influenza virus to about 50%, as in certain phages. Smaller 
viruses like paraviruses may have 3 to 4 genes while larger viruses like 
herpes and pox may have several hundred genes. Virions contain only a single 
copy of the nucleic acid. Hence they are called haploid viruses. The only 
exception is the retroviruses, which are said to be diploid as they contain 
two identical single- stranded RNA genomes. The virions are called the 
infectious particles. 

119 





The structure of nucleic acid in the virion may be either linear or 
circular. The DNA of most animal viruses in a linear molecule. In some plant 
viruses the genome is a circular RNA. But the RNA in animal viruses exists 
only as linear double stranded or single stranded molecule. 

Cultivation (culture) of Animal viruses: 

Viruses can grow only in living cells. However the culture of viruses 
is possible nowadays. The most economical and convenient method of 
cultivating a wide variety of animal viruses is the 'chicken embryo technique' . 
In this technique, fertile chicken eggs incubated for 5 to 12 days are 
inoculated with the virus particles through the shell, aseptically. The opening 
may be sealed with paraffin wax. The eggs incubated at 36°C are ideal sources 
for the growth of viruses. 

Chick embryos contain several different types of cells in which 
various viruses will undergo replication. The yolk sac is a general ideal 
medium for the growth of viruses. 

Viral cultures are of three types viz., Primary cell cultures, diploid 
cell strains and continuous cell lines. 

1. Primary culture: 

Primary cell culture are derived from normal tissue of an animal such 
as mouse, hamster, chicken and monkey or a human being. When cells from 
these tissues are processed and cultured the first monolayer is referred to as 
the primary culture. A monolayer is a confluent layer of cells covering the 
surface of a culture vessel. 

2. Diploid cell strain: 

Diploid cell strains are derived by primary cell cultures from a 
specific tissues like lung or kidney which is of embryonic origin. These 
diploid cells are the most employed host of choice for the production of 
human vaccine virus. 

3. Continuous cell lines: 

Continuous cell lines are capable of an infinite number of doublings. 
Such cell lines may arise with the mutation of a cell strain or more commonly 

120 



from the established cell cultures from malignant tissue. Many viruses, which 
are difficult or impossible to grow have been cultured in continuous cell lines. 

Viral Diseases: 

A. Cancer and Viruses: 

Viruses have been identified as one of the causative agents for 
cancer or tumour. Such tumour inducing viruses are called oncogenic 
viruses. Adenoviruses, polioma virus, simian virus 40 (SV 40), Epstein-Barr 
virus (EBV) ( a herpes virus) are oncogenic DNA viruses. The RNA sar- 
coma viruses are oncogenic RNA viruses (eg., Rous sarcoma). 

B. Rabies Virus and Rabies disease: 

Rabies virus belongs to the rhabdovirus family. It is a parasite of 
domestic and wild mammals. The transmission to humans occurs through the 
bite of an infected animal. Dogs, cats, bats, are the mammalian animal sources 
for the rabies virus. 

In humans, the symptoms of rabies are severe headache, high fever, 
alternating excitement and depression, muscular spasms in throat and chest, 
hydrophobia etc. The incubation time in humans is usually about 3 to 8 weeks 
but it may also vary. If untreated the mortality rate from rabies is 1 00 percent. 

The new rabies vaccine was discovered in 1980. It is an inactivated 
vaccine prepared from the virus propagated in cultures of diploid human 
cells. This vaccine is both safe and highly immunogenic. 

C. Pox virus: 

Pox viruses are the largest of all viruses and are brick shaped. They 
contain double stranded DNA, protein and lipid. They have a dumbell shaped 
nucleoid surrounded by two membrane layers. 

Variola virus is called the small pox virus. It is transmitted by droplet 
infection either directly from the infected person or by handling articles 
infected by the patient. Small pox is completely eradicated. The small pox 
vaccine consists of vaccinia, closely related to variola. It gives protection 
both by humoral and cell mediated immunity. 

Other pox viruses are chicken pox and measles viruses. 

121 



D. Hepatitis-B: 

Hepatitis B virus (HBV) is an enveloped virus with a double stranded 
DNA. This causes jaundice and hepatic carcinoma. This disease is deadly 
and more infective than AIDS. HBV vaccine consists of purified HBV Ag 
(Australian antigen) obtained from the blood serum of apparently healthy 
carriers. 

II. Bacteria - structure 

The structure, size and arrangement of bacterial cells consitute their 
morphology. 



. 



re 



-COCCI 



s= 



^o ■£: ' m- 




^ **=***: 



:0: 





bacilli spirillum 



vibrio 



bacilli 



Fig. 2.3. Morphology of bacteria 

The various morphological features are 

1 . They are spherical or rod like or spiral shaped. 

2. The arrangement of cells in pairs, clusters, chains, trichomes and filaments 
etc. 

3. The appendages are visible by special staining techniques or by electron 
microscopy. 

The above three features represent the gross morphological 
characteristics, which are of taxonomic importance in bacterial species 
identification. In addition, the bacterial cells possess elaborate internal 
structures, which constitute microbial cytology and bacterial anatomy. 

Bacterial Culture 

All bacteria need nutrients for their growth. They need a nutrient 

122 



medium for their growth and culture. A bacteriological medium is composed 
of known chemical compounds. It is called a chemically defined medium or 
synthetic medium, The compounds are carbohydrates, proteins, nucleic 
acids, lipids, vitamins and other complex organic substances. Certain 
complex materials include peptones, meat extract, yeast extract etc. The 
medium with the above raw materials can support the growth of a wide 
variety of heterotrophic bacteria. Agar is included as a non-nutritive 
solidifying agent. Nutrient agar and nutrient broth are the simple solid and 
liquid media for the growth of heterotrophs respectively. 

The preparation of bacteriological media involves the following steps. 

1 . Each ingredient or the complete dehydrated medium is dissolved in the 
appropriate volume of distilled water. 

2. The pH of medium is determined. 

3. Agar is added and the medium (solid medium) is boiled to dissolve agar. 

4. The medium is dispersed in flasks or tubes. 

5. The medium is sterilized by autoclaving. 

The growth of bacteria also require in addition to nutrients, physical 
conditions such as temperature, gaseous conditions and pH (acidity and 
alkalinity) and other miscellaneous requirements such as illumination, 
hydrostatic pressure, etc. 

Bacterial Genetics : 

In bacteria the cells have a single circular strand of DNA. It is not 
associated with proteins as are eukaryotic chromosomes. The bacterial genes, 
like the eukaryotic genes possess the features of replication, phenotype 
expression, mutation and genetic recombination etc. In bacteria the genetic 
recombination results from three types of gene transfer viz., conjugation, 
transduction and transformation. 

Conjugation involves the transfer of some DNA from one bacterial 
cell to another followed by the separation of the mating pair of cells. In this, 
large segments of the chromosomes and in special cases the entire 
chromosome may be transferred. 

123 



donor recipient 



plasmid DNA 




^X 




conjugation tube 



Fig. 2.4. Bacterial conjugation 

Bacterial transformation is a process in which cell free or naked DNA 
containing the genetic information is transferred from one bacterial cell to 
another. It was discovered by an English health officer, Griffith in 1928. The 
transforming principle was identified as DNA by Avery Macleod and Mc 
Carthyinl944. 

In transduction, a bacteriophages acts as a vector, transfering a portion 
of DNA from one bacterium (donor) to another (recepient). If all fragments 
of bacterial DNA have a chance to enter a transducing phage, the process is 
called Generalized transduction. On the contrary if a few restricted genes 
of the bacterial chromosomes are transduced by bacteriophage, it is called 
specialized transduction. 

Bacterial Diseases 

A. Salmonella and Human Diseases: 

Salmonella are pathogenic bacilli which cause three kinds of 
infection to humans viz., enteric fever (Typhoid or Paratyphoid), 
Gastroenteritis and Septicemia. 

Typhoid fever is caused by S.typhi. It is transmitted via Pathogen 
contained food and water. The disease is characterized by a continued 

124 



fever, inflammation of the intestine, formation of intestinal ulcers and 
enlargement of the spleen. 

Gastroenteritis is caused by Salmonella, but most commonly by 
S.choleraesuis. The bacteria reach the blood stream from the intestinal tract, 
where it multiplies. It causes recurring high fever, chills, loss of appetite and 
weight loss. When the bacteria infect the organs from blood they can cause 
meningitis, pneumonia, abscesses, nephritis, osteomyelitis, or endocarditis, 
etc. 

B. Cholera : 

Cholera is caused by Vibrio cholere. It is a disease of antiquity and 
has been the cause of untold sufferings and death. Cholera is transmitted in 
water and food contaminated with this bacteria. In the small intestine, the 
bacteria adhere to epithelium, multiply and produce the enterotoxin. The 
symptoms of cholera are vomiting, profuse diarrhoeal stool (rice water stool) 
Which results in severe dehydration, loss of minerals, increased blood 
acidity and haemoconcentration. 

C. Plague : 

Plague is caused by the bacterial species Yersinia pestis, a non motile 
gram negative bacilli. There are two types of plagues. They are bubonic 
plague and pneumonic plague. Bubonic plague is characterized by enlarged 
and inflamed lymph glands (Bubos). The symptoms are shivering, fever, 
nausea, vomiting and general weakness. In untreated cases the bubonic plague 
can cause 58% mortality. Pneumonic plague is a pneumonia characterized 
by a thin watery sputum with bright red streaks of blood. The mortality is 
100% in untreated cases. 

D. Syphilis: 

The disease syphilis is a well known and dreadful sexually 
transmitted disease (STD). It is caused by Treponema pallidium. Syphilis 
occurs only in humans and is transmitted by direct sexual contact (Venereal 
syphilis) or through placenta from an infected mother to the foetus 
(Congenital syphilis). Venereal syphilis progresses in three stages viz., 
primary, secondary and tertiary stage. The symptoms are very prominent in 

125 



the tertiary stage. It will lead to blindness, loss of hearing, brain damage, 
insomnia, headache and delusions and spinal cord damage. 

E. Gonorrhoea : 

Gonorrhoea is another sexually transmitted disease caused by 
Neisseria gonorrhoea. In the males the primary site of infection is the 
urethra. In the female it is the cervix. It causes pain during urination and a 
yellowish discharge from the urethra of males. In females also it causes 
painful urination and vaginal discharge. Other symptoms are fever, 
abdominal pain, arthritis, meningitis etc. 

III. Protozoan microbiology 

Protozoans are eukaryotic, single celled organisms, which are 
predominantly microscopic in size. The majority are between 5 to 250 
microns in diameter. Protozoan microbiology is mostly concerned with the 
disease aspects in humans. Some well known protozoan diseases in human 
beings are the intestinal amoebiasis, African sleeping sickness, and malaria. 
Several flagellate protozoans are responsible for diseases in both children 
and adults. Giardia intestinalis is associated with diarrhoea in children. 
Trichomonads are found in the mouth and cause gingivitis. 

A. Plasmodium and Malaria: 

Malaria is a mosquito borne disease caused by the protozoan, 
Plasmodium. The life cycle of malarial parasite comprises two phases namely 
the asexual phase in man and the sexual phase in the female Anopheles 
mosquito (Definitive host). 

Four different types of Malaria are recognized on the basis of period 
of recurrence of fever. They are 1 . Tertian, Benign Tertian or Vi vax malaria, 
caused by Plasmodium vivax. 2. Quartan Malaria caused by Plasmodium 
malariae 3. Mild Tertian or Ovale Malaria caused by Plasmodium ovale 
4. Malignant Tertian or Pernicious Malaria caused by Plasmodium 
falciparum Of the four, the malignant type is fatal. 

In malarial fever, the patient suffers from shaking chills, and 
sweating. As the chills subside, the body temperature may rise to 106 ° F. 
The high fever is induced by the toxic haemozoin granules, which are 

126 



liberated in plasma when the parasite schizonts burst out from the RBCS. 
The patient also suffers from severe anaemia due to destruction of 
erythrocytes. Other symptoms are enlargement of spleen, due to massive 
increase in the number of phagocytic cells of the lymphoid macrophage 
system. In the case of falciparum infection thrombosis of visceral capillaries 
occurs. Death takes place when the capillaries of brain are plugged with 
both the parasites and the malarial pigment. Another very serious outcome 
of the falciparum infection is black water fever. It is characterized by the 
wholesome destruction of patient's erythrocytes and the excretion of 
liberated haemoglobin in the urine. 

B. Amoebiasis 

Amoebiasis in man is due to the infection by the protozoan endopara- 
site (Sarcodina) Entamoeba histolytica. It is worldwide in distribution but, 
its prevalence is greater in tropics and sub tropics than in temperate zones. 
The vegetative trophozoite form is pathogenic. The trophozoites make their 
way deep into the sub mucosa of the large intestinal wall by eating through 
the intestinal mucosa. The blood and the ulcer contents pour into the lumen 
of the intestine and pass out as bloody stool. This characterizes the amoebic 
dy sentry or amoebiasis. 

C. Other pathogenic protozoans 

1. Trypanosoma gambiens - causes African sleeping sickness 

2. Leishmania donovani - causes kala azar 

3. Leishmania tropica - skin leishmaniasis 

Larval microbiology 

Larval microbiology deals with human diseases caused by parasitic 
larvae. Parasitic infections which man acquires from animals are known as 
zoonotic infections or zoonoses. In the zoonoses, human infections are only 
accidental events and the parasite is not benefited since the chain of 
transmission is usually broken with human infection. The term anthroponoses 
means infections with parasites species that are maintained in man alone. 
Malaria and filaria are examples. The term Zooanthroponoses refers to 
infections in which man is not merely an incidental host but an essential link in 
the life cycle of the parasite (eg., Beef and pork tapeworm). 

127 



Schistosomes or blood flukes 



" -■£ 




-female 




cercaria larva 
Fig. 2.5. Blood flukes 

Taenia solium (The Pork Tapeworm) 

Distribution - Taenia solium is found commonly in all parts of the world 
where pork is eaten without being properly cooked. It is an endoparasite. 

Habitat - Found inside the small intestine of man. 

External characters : The body of Taenia solium is long, dorsoventrally 
flattened, narrow, ribbon like reaching a length of six to ten feet. The body 
is divided into three parts viz (i) Head or scolex (ii) Neck and (iii) Strobila. 

Head (Scolex) :- The anterior end of the body of Taenia has a knob like 
part about the size of a pin-head called scolex. The scolex has a flat structure 
called the rostellum which can be protruded slightly. At the base of the 
rostellum, there is a double circlet of minute, chitinous curved hooks. The 
inner circle contains larger hooks and outer circle has smaller hooks. The 
hooks help to fix the scolex firmly to the wall of the host intestine. The scolex 
also has cup like four suckers on the four sides. The suckers and hooks 
help the parasite for attachment to the intestinal wall of the host. 

rostellum 
hooks 

sucker 



neck 




Fig.2.6. Scolex of taenia solium 

128 



Neck : The scolex is followed by a thin, narrow, unsegmented neck region. 
New segments called proglottides (sing, proglottis) proliferate from this region 
by transverse fission. Hence it is konwn as the region of proliferation. As 
the region of proliferation grows and produces new proglottides, the older 
ones are pushed back and gradually enlarge in size. The process of formation 
of new proglottides is known as strobilization. 

Strobila : The rest of the body consituted by proglottides is known as 
strobila. The strobila of a mature tape worm contains about 800 to 900 
segments. It hangs freely in the lumen of the intestine of the host. The segments 
are divided into three regions on the basis of the genital development. 

(a) Immature proglottides : These are broader than long and have their 
sex organs in the process of formation or without sex organs. These are 
found in the anterior region of the body 

(b) Mature proglottides : They have fully developed sex organs. 

(c) Ripe or gravid proglottides : These are found at the posterior most 
region of the body and are filled with fertilised eggs. 

Life cycle - The fully developed gravid proglottides at the posterior end 
get detached singly or in short chains (or groups). As the old gravid 
proglottides get detached, new segments are added in the neck region and 
the length of the worm remains constant. Some of the eggs escape out of 
the gravid proglottides. Therefore, both gravid proglottides and free eggs 
are passed out along with the faeces of an infected person. 

The gravid proglottides and the eggs may be swallowed along with 
the faeces by the pig which is the intermediate host. On reaching the stomach 
of the pig, all the eggs escape out of the gravid proglottides. 

The egg is whitish in colour and spherical in shape. In the centre 
of the egg, there is an embryo called Onchosphere or Hexacanth. The 
embryo is protected by a thick shell. The onchosphere possesses three pairs 
of minute hooklets (or hooks). 

On reaching the small intestine of the pig, the onchosphere penetrates 
the wall of the small intestine and enters into the blood stream. Ultimately 

129 



Suckers 



Tapeworm head 
greatly enlarged 







■ ft- 1 . -."■'■ *- fc _ r c 



Newly formed 
segments 



Primary host's intestine wall 
with tapeworm head 
embedded in it 
Bladder with head 
pushed out 



Primary host (e.g. man) 
Secondary host (e.g. pig) 




Ripe segment N 

breaks away from \ 
tapeworm body 



Segment full of \ 

eggs passes out of \ *?r. 

primary host with \ £\3l 

excreta 



Fluid-filled bladder 

Bladderworm inside 
muscle is eaten by 
primary host 

Embryo with six 
S X hooks bores thorugh 
stomach wall into 
blood vessel 



isp^@<^fe 




Fig. 2.7. Life cycle of the pork tapeworm 

130 



the onchosphere settles in the skeletal muscles. The onchosphere may settle 
in almost any part of the body. Then it develops into a minute bladder-like 
structure. This stage is called the cysticercus or bladder worm. The 
cysticercus gets fully developed at the end of two months. 

The cysticercus is whitish in colour and oval in shape. The cysticercus 
of Taenia solum is called 'cysticercus cellulose'. It carries a small scolex 
enclosed in a cavity. The cysticercus can remain embedded in the muscles 
of the pig for many years. In the body of the pig, the cysticerci are found 
mainly in the striated muscles. In some cases they may be found in liver 
and lungs. 



GRAVID 

raoGLorriDES 




CYSTICERCUS 



ONCHOSPHERE 



CYSTICERCUS ^ C ' 

CELLULOSE 

Fig. 2. 8. Schematic representation of life cycle of Taenia solium 



131 



Man gets infected by eating raw or improperly-cooked pork containing 
cy sticerci. Pork containing cysticerci is described as 'Measly pork' . On reaching 
the small intestine of man, the bladder portion of the cysticercus gets 
disorganised and the scolex escapes out. The scolex then attaches itself to 
the mucous membrane and begins to develop proglottides. The full adult 
stage is reached after a period of three months. For this parasite, man is 
the definite host and the pig is the intermediate host. 

Pathogencity or parasitic effect : The disease caused by adult Taenia 
is known as Taeniasis. The disease caused by bladder worm infection is 
called cysticercosis. Taeniasis is characterised by abdominal pain, indigestion, 
vomiting, loss of appetite and nervous disorders. Tapeworm blocks the 
alimentary canal passage. 

Treatment : For treatment of Taenia infections antihelminthic drugs may 
be administered in prescibed dose. 

Control : (1) Measures against indiscriminate defaecation. 

(2) Proper disposal of night-soil or faeces. 

(3) Proper cooking of the pork. 

(4) It is important to detect and treat persons has adult worms 
as they can develop cysticercosis due to autoinfection. 

Ascaris lumbricoides (The Round worm, Giant intestinal worm) 

Distribution. This worm is found thoughout the world except very cold 
regions. 

1. Habitat : The round worm, Ascaris lumbricoides is the largest nematode 
parasite in the human intestine. 

External Characters 

Ascaris lumbricoides is an endoparasite found in the small intestine 
of man. The body is long and cylindrical in shape with pointed ends. It has 
an unsegmented body with dull reddish yellow colour. The mouth lies at the 
anterior end and is provided with three finely toothed lips (one dorsal and 
the other two are venterolateral). The lips are provided with two pairs of 
sensory papillae. 

132 



The worms show sexual dimorphism ie sexes are separate. They differ 
in the following ways. 

1. Male worm is about 15-30cm in length and the female worm is about 
20-40cm in length. 

2. The posterior end of the female is straight, whereas that of the male is 
curved ventrally like a hook. 

3. Anus is present in the female and the cloacal aperture in the male. 

4. In the female, the genital aperture is distinct from the anus and lies ventrally 
about a third of the length of the body from the anterior end, whereas in 
the male, there is a single aperture, the cloacal aperture which serves both 
as the anus and the genital opening. 

5. Two curved chitinous spicules are projecting from the cloacal aperture 
in male only. 

A little behind the anterior end a median excretory pore is present 
on the ventral side in both the sexes. Four longitudinal streaks or lines are 
present on the body wall extending from end to end of the animal. (One 
mid dorsal, one mid ventral and two lateral in position). 

The body is covered by a thin cuticle which is secreted by the 
underlying epidermis. The mouth is at the anterior end of the body guarded 
by three lips or oral papillae. The alimentary system is poorly developed 
with a mouth, pharynx, intestine, rectum and anus. 

Life cycle : The male and the female worms come into sexual union after 
which the female worm lays about two lakhs (2,00,000) eggs per day. The 
eggs are passed out along with the faeces. The eggs which are freshly passed 
out are not infective to man. After a period of 16 to 20 days, a small larva 
develops inside the egg. The egg is now called embryonated egg. Only the 
embryonated eggs are infective to man. 



133 




. mature egg containing larvae 



rhabditiform larva 



■ swallowed larva 
hatches out in 
duodenum 



Fig. 2.9.Life cycle of Ascaris lumbricoides 



t 



-+LARVA >■ 4th MOULT i-LARVA »ADL LI-J-EQGS i 
LARVA \ / | 

\ SMALL /IffiSL 

3rd MOULT \ INTESTINE / t^** 

IIH I ■■Am; 

t 

LARVA LUNGS/' 

if. EMBRTON'ATED 

%A OUTSIDE 

ty ,' THE HUMAN 

BODY 

(EXOGENOUS 

«M.*~ jams 

[16to2fldays] y ETC 

(Viability of egga I FOOD 
for S to 6 years) I / / 



2nd MOULT 
."Hid** 



LARVA 





WATER 



.' .' 



SWALLOWING 
Fig. 2.10.Schematic representation of life cycle of Ascaris lumbricoides 

134 



The egg is broadly oval in shape with a thick shell. The shell is 
surrounded by another colourless albuminous layer. The eggs are highly 
resistant and are not affected by desiccation, freezing or by the usual strength 
of disinfectants. However, the eggs are killed in direct sunlight. The eggs 
of Ascaris can live for five to six years. 

The eggs are found in water, food, on exposed sweets, fruits etc., 
since the eggs are carried away by wind. So they can easily settle down 
on sticky surfaces such as sweets, water melons, cut fruits etc. 

Man gets infected by swallowing the embryonated eggs along with 
contaminated water and food. The infection is generally through ingestion. 
On reaching the small intestine, the egg hatches and a tiny larva measuring 
about 200mm to 300mm escapes out. This larva sheds its outer skin 
immediately. It is the first moult. Now it is called rhabditi form larva. The 
larva then penetrates the wall of the small intestine and reaches the blood 
stream. The larva is then carried to the right auricle and right ventricle and 
reaches the lungs ultimately. On the fifth day the larva sheds the outer skin 
which is the second moult. On the tenth day another moult takes place, the 
third moult. (Second and third moults take place in the lungs). Now the larva 
is about 1 to 3 mm. in length. The larva then goes through the bronchiole, 
the bronchus and reaches the trachea. Later, the larva is coughed out into 
the pharynx and from there it goes down the oesophagus and reaches the 
small intestine. On the 25th day the larva sheds its outer skin which is the 
fourth moult. After a period of two to two and a half months of infection, 
the adult stage is reached. The development outside the human body is termed 
as Exogenous phase. 

Pathogenicity : Infection with this worm is called 'Ascariasis' . The common 
symptoms are loss of appetite, intestinal pain, abdominal discomfort with 
indigestion. It also causes disturbed sleep in children. Appendicitis may also 
be caused by the worms blocking the appendix. If a large number of adult 
worms are present, they may get twisted together and cause mechanical 
obstruction of the intestine. Such a blockage or obstruction may be fatal 
if not surgically removed. 



135 



Control : 

1. Measures against indiscriminate defaecation. 

2. Protection of water against contamination by embryonated eggs. 

3. Proper disposal of night-soil 

4. Covering of sweets and other edibles from getting contaminated 
by embryonated eggs. 

5. Fruits, vegetables etc. should be washed before use. 
Pathogenecity of Microorganisms: 

Pathogenecity refers to the ability of microorganism to cause the 
disease in animals and humans. Infectious diseases more often result due to 
the interactions between the disease producing pathogenic microorganisms 
and host organisms. 

The Pathogenic adaptations 

The Pathogenecity of the microbes is due to several phenomena or 
adaptations. 

1 . Pathogens are able to selectively attach to the external surfaces such as 
the skin and conjunctiva or the internal surfaces such as the mucus 
membranes of the respiratory, gastrointestinal or urinogenital tracts. 

2. They also penetrate the above body surfaces and gain access to the 
internal tissues. 

3. In some infections, the pathogen may remain localized, growing near its 
point of entry into the body. 

4. Some pathogens become widely distributed in different tissues or organs. 
This is called generalized infections. 

5. Some other pathogens can grow within the cells of host, causing severe 
disturbances to normal physiological processes. 

6. Yet another group, may grow extracellularly and bring damage to the body 
tissues by elaborating substances called toxins. 



136 



The pathogenecity differs in different strains of pathogenic species. 
Some strains are highly virulent. In the case of virulent strains, only a few 
bacterial cells may suffice to cause disease in a host. On the contrary, other 
strains may be less virulent, and large numbers of cells may be needed to 
cause the disease. Some strains may be avirulent, and are incapable of 
causing the disease even when large numbers of cells are inoculated into the 
host. Such avirulent strains are called attenuated strains. These are widely 
used as vaccines to elicit the immunity. 

Antimicrobial Resistance: 

Pathogenic microbes are provided with their own mechanisms to 
establish infection in the host animals and humans. Similarly the hosts body 
has a number of defense mechanisms to mount resistance against the 
invasion and to prevent infection of pathogens. The antimicrobial response 
of hosts may be natural, non-specific and specific. 

Natural resistance includes species resistance, racial resistance and 
individual resistance. 

Chemotherapy 

The control and treatment of infectious diseases with a chemical 
compound or drug is called chemotherapy. The chemical compounds and 
drugs are called chemo therapeutic agents. 

A good chemotherapeutic agent posses the following characteristics: 

1 . It destroys or prevents the activity of a disease causing pathogen, without 
injuring the host tissues 

2. It is able to penetrate the cells and tissues of the host and can encounter 
the pathogens in effective but safe concentrations or dosage. 

3. It leaves the hosts natural defense or immune mechanisms such as 
phagocytosis or antibody production, unaffected. 

4. It exhibits selective toxicity, that is it kills or inhibits the pathogenic 
microbes without having harmful effect or having least harm to the host. 



137 



Antibiotics and Chemotherapy: 

Antibiotics are special and unique type of chemo therapeutics agents 
obtained from living organisms such as bacteria or fungi. The word antibiotic 
refers to a metabolic product of one microorganism that in very small amounts 
is detrimental or inhibitory to other microorganisms. The first antibiotic that 
was discovered was Penicillin from the fungus, Pencillium sp. by Alexander 
Flemming in 1929. Since then hundreds of antibiotic substances have been 
isolated. 

Antibiotics are of two types. 1. Broad spectrum antibiotics can 
destroy or inhibit many different species of pathogens. 2. Narrow spectrum 
antibiotics can destroy specifically some or few species of pathogens. 

The mode of action of antibiotics may be either bactericidal or 
bacteriostatic. The former destroys the microbial cells while the latter 
inhibits the growth of them. Moreover, the antibiotics may inhibit cell wall 
synthesis or disrupt the cell wall or damage the cytoplasmic membrane or 
inhibit the protein synthesis and nucleic acid synthesis (purine and 
pyrimidines); inhibit the specific enzyme systems and also inhibit the 
metabolic pathway of pathogens through competitive inhibition of key 
enzymes. 

Some notable antibiotics are Ampicillin, Streptomycin, Tetracyclin 
and Erythromycin etc. Some antifungal antibiotics are Griseofulvin and 
Imidazole etc. Some antiviral antibiotics are Amantidine and Cycloguanosine. 
The more promising chemotherapeutic agent for treating viral diseases is the 
Interferon. Interferons are glycoprotein molecules secreted by the leucocytes 
and fibroblasts. Some of the antitumour antibiotics are of the anthromycin 
group. 

AIDS (HIV) and its control 

The disease Acquired Immuno Deficiency Syndrome (AIDS) was 
identified in the year 1981 (December). Early epidemiological studies have 
established that it is a communicable disease transmitted through sexual 
contact or through blood and blood products. In 1983 Luc Montagnier at 

138 



Pasteur Institute^ Paris and Gallo at National Institute of Health (NIH) USA 
isolated the virus that caused AIDS. In 1986, the committee on 
taxonomy of virus coined the term HIV or Human Immunodeficiency Virus 
to avoid confusion due to different names being given by different reasearchers. 

HIV is new member of the Lentivirinae subfamily of human 
retroviruses. Retroviruses are RNA viruses, which have the capacity to 
convert their RNA into DNA with the help of an enzyme called reverse 
transcriptase. 

Structure of HIV: 



gpl20 

rt^fe&o gp41 

r - ~.i-yy,fm \ ,':_■ - . M reverse transcriptase 

^ *ff^N . ,'■■ ,p RNAhelix 



Fig. 2.11. Structure of HIV 

HIV is spherical in shape. Its size is about 100-140 nm. Like any 
other virus, it is made up of a central icosahedral capsid core containing the 
genetic material surrounded by a protein envelope. The protein envelope is 
attached several spicules of glycoprotein, Like other retroviruses the 
glycoprotein sticks out on both sides (inside and outside) of its protein coat. 
The outer position of glycoprotein called gpl20 is attached to the gp 41 
situated on the inner side of the viral coat, gp 41 is an unusually long protein 
with over 100 amino acids, gp 120 appears like a knob. Electron 
microscopic studies have revealed that the distribution of proteins of the viral 
surface is very much like a soccer ball made of 12 pentagons and 20 
hexagons, stitched together to make a sphere. The envelope of HIV also 
contains other proteins including some HLA antigens (Human Leucocyte 
Antigen). 

The genome of HIV contains two helix of RNA molecules in folded 
form. The enzyme reverse transcriptase is attached to RNA. 



139 



Pathogenesis: 

HIV causes profound immunodepression in humans. It is due to the 
depletion of one type of WBC, which is involved in the formation of 
antibodies called CD 4 plus T- helper cells (lymphocytes). In addition other 

, nucleic acid 

-envelope 

■ protein of envelope 




plasma membrane 



nucleic acid copies 



ryf new capsid 
proteins 



fjr^ newly assembled virus 
\ 



@u 



^"sS^^T 




Fig. 2.12. Viral multiplication 

cells such as B-lymphocytes and macrophages are destroyed by HIV 
infection. The infected macrophages serve as the reservoir of viruses and 
dissimulate to all tissues in the body. HIV is found besides blood, in all body 
fluids such as semen, vaginal secretion, cervical secretion, breast milk, CSF, 
synovial fluid, pleural fluid, peritoneal fluid, pericardial fluid and amniotic 
fluid. HIV can even destroy the brain cells. 

Symptoms: 

The following symptoms have been defined by WHO. 

1. Weight loss at least 10% body weight 

2. Chronic diarrhoea for more than a month 

3. Prolonged fever for more than one month 

4. Night sweats and persistent coughs 



140 



5. Opportunistic infections such as tuberculosis, oropharyngeal 
candidiasis (fungal infection in mouth and throat) 

6. recurrent herpes zoster (viral) infection 

7. Meningitis and nerve damage 

8. Loss of memory and intelligence 

9. An unusual cancer, kaposis sarcoma which produces scattered 
purplish lesions over the chest and abdomen. 

Diagnosis: 

ELISA test (Enzyme Linked Immuno Sorbent Assay) is a sensitive 
preliminary blood test used to detect HIV antibodies. 

Western Blot is the confirmatory test, which is highly specific and 
based on specific antibodies to viral core proteins. 

Control and Management: 

1. Screening of blood and blood products. 

2. Education to people about do's and don'ts in AIDS contraction and 
bringing more awareness among the public. 

3. Education about protected sexual behaviour and practices 

4. Participation of voluntary agencies, teachers, NGOs, paramedical 
workers, several other voluntary health organizations, in AIDS awareness 
programmes 

5. Making the antiretro viral drugs such as AZTs (Azidothymidine/Zidovudin) 
and saquinovir etc., available to patients. 

The management of HIV infection involves the above general 
measures, treatment of opportunistic infections and cancer, antiretro viral 
drugs, immunomodulators and supportive treatment and counselling. 



141 



3. IMMUNOLOGY 

Animals and human beings are continually exposed to various 
infectious agents like bacteria, viruses, fungi and parasites. It has long been 
noticed that survivors of certain diseases, e.g., measles, are not attacked by 
the same disease again. Clearly, these people have become immune to the 
concerned disease. The system of animal body, which protects it from 
various infectious agents and cancer, is called Immune system. A study of 
the immune system is known as Immunology. This chapter introduces the 
fundamental concepts of immune system and their use for the improvement 
of human health and welfare. 



The Latin term "Immunis", meaning "exempt" or "freedom", gave 
rise to the English word immunity. It refers to all the mechanisms used by the 
body for protection from environmental agents that are foreign to the body. 
These agents may be microorganisms or their products, certain food items, 
chemicals, drugs and pollen grains. Immunity is of two types : (a) innate, and 
(b) acquired immunity. 

sebaceous glands 



tears 

mucus 

saliva 

cilia 

intact skin 
mucus 

sweat 



Fig. 3.1. Natural immunity 



urination 
defaecation 



lowpH 




142 



A. Innate Immunity (Non-specific): Innate immunity comprises all those 
natural defense mechanisms with which an organism is protected from infec- 
tion. As a strategy, innate immunity consists of various types of barriers that 
prevent entry of foreign agents into the body. The pathogens that enter into 
the body, are quickly killed by some components of the immune system. This 
is the first line of defence in most animals. Innate immunity consists of the 
following four types of barriers. 

1. Anatomical Barriers : These barriers block the entry of organisms into 
the body. The skin and the mucous membrane lining the respiratory and 
intestinal as well as the reproductive passages constitute the barriers. 
Mucous material entraps foreign microorganisms. The ciliary movements 
produced by the epithelial lining cells expel out micro-organisms from the body. 

2. Physiological Barriers : Factors like body temperature, pH and various 
body secretions, prevent the growth of pathogenic micro-organisms. For 
example, fever response inhibits growth of many pathogens. Acidity of the 
stomach contents due to HCI secretion kills ingested micro-organisms. 
Lysozyme present in secretions, such as tears and saliva, digest bacterial 
cell walls. Certain cells, like WBC, when infected with a virus, respond by 
releasing anti viral proteins, called interferons. Interferons, in turn, make 
the cells in the vicinity resistant to viral infections. As a result, the concerned 
persons exhibit increased resistance to viral infections. 



phagolysosome 
phagosome 

bacteria 

phagocyte 
Fig. 3.2. Phagocytosis 

3. Phagocytic Barriers : Phagocytosis is an important mechanism of innate 
immunity. It is performed by leucocytes. In response to pathogenic 
infections, the total count of leucocytes will increase sharply. Humans 
contain wandering phagocytes that circulate throughout the body. The most 
important phagocytes are the macrophages and the neutrophils. 
Macrophages are large irregular- shaped cells that engulf microbes, viruses 
and cellular debris. In response to an infection, monocytes are liberated at 

143 




the site of infection. These monocytes get converted into macrophages. These 
cells are provided with bacteriolytic enzymes and free radicals, which 
destroy the pathogens. 

4. Inflammatory Barriers : Usually an infection or tissue injury results in 
redness and swelling, along with pain and production of heat that may result 
in fever. The above phenomenon is known as inflammatory response. This 
response occurs due to release of chemical alarm signals, notably 
histamine, serotonin and prostaglandins, by the damaged mast cells. 
At the site of inflammation there may be leakage of vascular fluid, which 
contains serum proteins with antibacterial activity. Further, there is an influx 
of phagocytic cells into the affected area. These responses inhibit and 
destroy the invading microorganisms. 

Besides the phagocytes, natural killer cells (NK cells) (T 
Lymphocytes) kill virus-infected cells and some tumour cells of the body by 
creating perforin-lined pores in the plasma membrane of the target cells. These 
pores allow entry of water into the target cell, which then swells and bursts. 

Acquired Immunity (Specific immunity) 

Acquired immunity, also known as adaptive or specific immunity, is 
capable of recognizing and selectively eliminating specific microorganisms. 
Acquired immunity is found only in verterbrates. It supplements the 
protection provided by innate/natural immunity. It is generated in response 
to an exposure or encounter to the microorganisms in question. Specific 
defence mechanisms require several days to be activated, following the 
failure of non-specific defence mechanisms. Adaptive immunity has the 
following unique features. 

(i) Specificity : It is the ability to distinguish differences among various 
foreign molecules. 

(ii) Diversity : It can recognize a vast variety of foreign molecules. 

(iii) Discrimination between Self and Non-self : It is able to recognize and 
respond to molecules that are foreign (non-self) to the body. At the same 
time, it can avoid response to those molecules that are present within the 
body (self antigens) of the given animal. 

144 



(iv) Memory : When the immune system encounters a specific foreign agent, 
e.g., microbe, for the first time, it generates an immune response and 
eliminates the invader. The immune system retains the memory of this 
encounter for a prolonged interval. As a result, a second encounter with the 
same microbe evokes a heightened immune response. 

Specific immunity employs two major groups of cells : 
(a) lymphocytes, and (b) antigen presenting cells. A healthy individual 
possesses about a trillion of lymphocytes. The lymphocytes are of two types 
viz., T- lymphocytes or T-cells and B - lymphocytes or B - cells. Both 
the types of lymphocytes, as well as the other cells of the immune response, 
are produced in bone marrow. The process of their production is called 
haematopoiesis. Some immature lymphocytes, destined to become 
thymocytes, migrate via blood to the thymus, where they mature and 
differentiate as T - cells. The B- cells, on the other hand, mature in the bone 
marrow itself. The B and T cells, together, generate two types of specific 
immunity, viz., (a) cell-mediated and (b) antibody-mediated or 
humoral immunity respectively. 

(a) Cell-mediated Immunity (CMI) 

Cell-mediated immunity is the responsibility of a subgroup of T cells, 
called cytotoxic T lymphocytes (CTLs). An activated cytotoxic lymphocyte 
is specific to a target cell, which has been infected, and kill the target cell by 
a variety of mechanisms. This prevents the completion of life cycle of the 
pathogen and its growth, since it depends on an intact host cell to do that. 
Cell-mediated immunity is also involved in killing of cancer cells. 

(b) Antibody-mediated Immunity / Humoral Immunity 

Antibody mediated or humoural immunity involves the synthesis of 
specific antibody molecules called immunoglobulins by the B-lymphtocytes. 
Each antigen has many different antigenic determinants, each of which 
matches a specific antibody and binds to it. The B cells, direct the antibody- 
mediated immunity. The antibody molecules (Igs) may be bound to a cell 
membrane in the form of receptors or they may remain free. The free 
antibodies have three main functions viz., 1 . agglutination of particulate 
matter, including bacteria and viruses, 2. opsonisation or coating over 
bacteria to facilitate recognition and phagocytosis by the phagocytes and 
3. neutralization of toxins released by bacteria. 

145 



Adaptive immunity may be active or passive. Active immunity is 

due to the immune response generated in the individual in question by a 
pathogen or vaccine, whereas passive immunity is conferred by transfer 
of immune products, like antibodies, etc., from an individual into a 
non-immune individual. 
Activation of Adaptive Immunity 

Every antigen is processed by antigen presenting cells(APC), like 
macrophages, B lymphocytes and dentric cells. The processed antigen is 
presented on the surface of these cells. A subgroup of T cells called T helper 
cells, specifically interacts with the presented antigen and becomes 
activated. The activated T helper cells then activate B cells, and a subgroup 
of T cells called cytotoxic lymphocytes (CTLs), in a specific manner. The 
activated B and cytotoxic lymphocytes proliferate to produce clones. All the 
cells of a clone can recognize the same antigen and eliminate it. 



LYMPHOIDAL ORGANS 0- 




cervical node 
thymus 



pit node 
spleen 

peyer's node 
— groin node 

bone marrow 



Fig. 3.3. Various Lymphoid organs of Human 

146 



Structure and Functions of the Immune System 

The lymphoid system consists of the lymphoid cells (lymphocytes 
and plasma cells) and lymphoid organs. Based on different roles they 
perform, lymphoid organs can be classified into central (primary) and 
peripheral (secondary) lymphoid organs. The central lymphoid organs are 
lymphoepithelial structures in which the precursor lymphocytes proliferate, 
develop and acquire immunological capability. In mammals, the bone 
marrow, the thymus and the bursa of fabricius in birds represent primary 
lymphoid organs. After acquiring immunocompetence, the lymphocytes 
migrate along blood and lymph streams, accumulate in the peripheral 
lymphoid organs and, following antigenic stimulus, effect the appropriate 
immune response. The spleen, lymph nodes and mucosa - associated 
lymphoid tissue (MALT) constitute the major peripheral or secondary 
lymphoid organs. Lymphoidal tissues in the gut ( peyer's patches), 
appendix, tonsils, salivary glands, tear glands and also the secretion 
(colostrums) of the lactating breast of the mother also are included in the 
immune sysytem. 

I. Primary Lymphoid Organ 
Thymus : 

The thymus develops at about the sixth week of gestation. By eighth 
week, it grows into a compact epithelial structure. Mesenchymal stem cells 
(precursors of lymphocytes) from the yolk sac, foetal liver and bone marrow 
reach the thymus and differentiate into the thymic lymphoid cells (thymocytes). 




capsule 
nurse cell 

trabecula 

epithelial cell 

dendritic cell 

Hassal's corpuscle 



Fig. 3.4. Thymus entire 



Fig. 3.5. ThymusCS 

The thymus acquires its characteristic lymphoid appearance by the 

third month of gestation. It is thus the first organ in all animal species to 



147 



become predominantly lymphoid. In human beings, the thymus reaches its 
maximal size just prior to birth. Thymus continues to grow till about the 12 th 
year. After puberty, it undergoes spontaneous progressive involution, 
indicating that it functions best only in early life. 

The thymus is located just behind the upper part of the heart. It has 
two lobes surrounded by a fibrous capsule. Septa arising from the capsule 
divide the gland into lobules which are differentiated into an outer cortex 
and an inner medulla. The cortex is crowded with actively proliferating 
small lymphocytes. The medulla consists mainly of epithelial cells and mature 
lymphocytes amidst which are the hassall's corpuscles, which are whorl-like 
aggregations of epithelial cells. 

The thymus was considered as an organ without any recognized 
function. But its role in the development of cell mediated immunity has been 
found recently. The primary function of the thymus is the production of 
thymic lymphocytes(T cells). It is the major site for T lymphocyte 
proliferation in the body. However, of the lymphocytes produced, only about 
one per cent leave the thymus. The rest are destroyed locally by programmed 
cell death or apoptosis. In the thymus, the lymphocytes acquire new surface 
antigens (Thy antigens). Lymphocytes produced in the thymus are called 
'thymus (T) dependent lymphocytes' or 'T cells'. Unlike, lymphocytes 
proliferation in the peripheral organs, the function of thymus is independent 
of antigenic stimulation. 

The thymus confers immunological competence on the lymphocytes 
during their stay in the organ. Prethymic lymphocytes are not 
immunocompetent. In the thymus they are 'educated' so that they become 
capable of mounting cell mediated immune response against appropriate 
antigens. This is effected by hormone-like factors produced by the thymus 
such as thymulin, thymosin and thymopoietin. The importance of thymus 
in lymphocyte proliferation and development of CMI is evident from the effects 
of lymphopenia, and in neonatally thymectomised mice. 

T lymphocytes are selectively seeded into certain sites in the 
peripheral lymphatic tissues. These are found in the white pulp of the spleen, 
around the periarteriole region, and in the paracortical areas of lymph nodes. 



148 



II. Peripheral Lymphoid Organs 
A. Lymph nodes : 



inlet duct 



follicles 
capsule 




lymphatic artery 

lymphatic vein 

outlet duct 

Fig. 3.6. Lymph node - C.S 

The lymph nodes are small, round or ovoid bodies placed along the 
course of lymphatic vessels. They are surrounded by a fibrous capsule from 
which trabeculae penetrate into the nodes. The node can be differentiated 
into an outer cortex and an inner medulla. In the cortex are accumulations 
of lymphocytes (primary follicles) within which germinal centers (secondary 
follicles) develop during antigenic stimulation. The follicles contain, besides 
proliferating lymphocytes, dendritic macrophages which capture and pro- 
cess the antigen. In the medulla, the lymphocytes are arranged as elongated 
branching bands (medullary cords). The cortical follicles and medullary cords 
contain B lymphocytes and constitute the bursa or bone marrow dependent 
areas. Between the cortical follicles and medullary cords, there is a broad, 
intermediate zone called paracortical area which contains T lymphocytes and 
constitutes the thymus dependent area. 

Lymph nodes act as a filter for the lymph. Each group of nodes drain 
a specific part of the body. They phagocytose foreign materials including 
microorganisms. They help the proliferation and circulation of T and B cells. 
They enlarge following local antigenic stimulation. In the human body, totally 
about 600 lymph nodes are distributed. 



149 



B. Spleen : 

It is the largest lymphoid organ. It contains red and white pulp regions 
that serve as filters. The macrophages within the spleen help to remove and 
destroy pathogens. 

Functions of Spleen : 

1 . The spleen serves as the graveyard for effete(aged) red blood cells, 2. It 
acts as a reserve tank and setting bed for blood and 3. It acts as a systemic 
filter for trapping circulating blood borne foreign particles. (The 
immunological function of the spleen is primarily directed against blood borne 
antigens). 

III. Secondary Lymphoid Organs 

Mucosa associated lymphoid tissues (MALT) : 

The mucosa lining the alimentary, respiratory, genitourinary and other 
lumina and surfaces are constantly exposed to numerous antigens. These 
areas are endowed with a rich collection of lymphoid cells, either specialized 
aggregates as the Peyer's patches or Scattered isolated lymphoid follicles 
- collectively called the Mucosa associated lymphoid tissues (MALT). 
Such lymphoid tissues in the gut are called Gut associated lymphoid tissue 
(GALT) and those in the respiratory tract are called Bronchus associated 
lymphoid tissue (BALT). MALT contains lymphoid cells as well as 
phagocytic cells. Both B and T cells are present. The mucosa is endowed 
with secretory IgA. The mucosal regions afford/confer protection from many 
enteric and respiratory infections. 

Antigens 

The terms immunogen and antigen are often used synonymously. 
However, these terms imply two closely related entities. The first describes a 
molecule that provokes an immune response(immunogenicity) and hence is 
called an immunogen. The other describes a molecule which reacts with the 
antibody produced, or with the activated cellular constituents of cell 
mediated immunity(antigenicity), and is referred to as an antigen. 



150 




antigen epitope 
antibody 



Fig. 3.7. Antigen - Antibody binding 

In contrast to this is the hapten. Haptens are small well defined 
chemical groups such as dinitrophenol (DNP) which are not immunogenic on 
their own but will react with preformed antibodies. To make a hapten immu- 
nogenic, it must be linked to a carrier molecule which is itself immunogenic. 

Antigens are recognized not only by antibodies, but also by antigen 
specific T cell receptors. In contrast to immunoglobulins, which usually 
recognize intact antigens, T cell surface receptors recognize processed 
antigens on the surface of antigen presenting cells. 

Antigenic determinants and epitopes 

The part of the antibody molecule which makes contact with the 
antigen is termed the paratope. Consequently, the part of the antigen 
molecule that makes contact with the paratope is called the epitope. As 
most antigens are protein in nature, they exist in a folder, three dimensional, 
tertiary structure. Hence there may be a cluster of amino acid sequences on 
the three dimensional structure constituting a series of epitopes. Each of these 
epitope clusters on the antigen are known as an antigenic determinant. 

Generally the substances, which are capable of eliciting an immune 
response, that is, the synthesis of antibodies are called antigens. However 
the above definition of antigens do not infer the cell mediated response. Hence 
the term immunogen is introduced to denote antigenic substances which elicit 
both humoral and cell mediated immune response or either humoral or cell 
mediated response. 



151 



Antigens may be either natural or artificial/synthetic ones. Natural 
antigens, fall into two categories viz., particulate antigens and soluble 
antigens. Bacteria, viruses, erythrocytes and cells represent particulate type 
antigens. Bacterial toxins, proteins, carbohydrates, glycoproteins and 
lipoproteins represent the soluble antigens. 

In addition, a variety of chemical compounds, biological 
macromolecules, synthetic polypeptides are regarded as potential antigens. 
Several polysaccharides, nucleoproteins and lipoproteins are also considered 
as antigens. Recently antibodies to DNA have been used in immunization. 

Antibodies - Immunoglobulins 

Immunoglobulins (Igs) are glycoproteins. Each molecule of Ig 
consists of two pairs of polypeptide chains of different sizes. The smaller 
chains are called 'light' (L) chains and the larger ones are called 'heavy' 
(H) chains. The L chain has a molecular weight of approximately 25,000 and 
the H chains is of 50,000. The L chain is attached to the H chain by a 
disulphide bond. The two H chains are also joined together by 
S-S bonds, depending on the class of immunoglobulins. The H chains are 
structurally and antigenically distinct for each class and are designated by the 
Greek letter corresponding to the immunoglobulin class, as follows : 

IgG (Gamma) IgA (alpha ) IgM(mu) Igd (delta) and IgE (epsilon) 

heavy chain 
amino end 

light chain 




hinge 



S-S bridge 
COOH end 



Fig. 3.8. Immunoglobulin (IgG) 

The L chains are similar in all classes of immunoglobulins. They 
occur in two varieties, kappa (k) and lambda (X). A molecule of 
immunoglobulin may have either kappa or lambda chains, but never both. 

152 



Region of polypeptide chains : 

Each heavy and light chains consists of two regions viz., 

l.The variable (V) region or Fab region: The V region shows a wide 
variation in amino acid sequences in the amino or N-terminal portion of the 
molecule. These areas of high variability in the variable region of H and L 
chains are called 'hotspots' or hypervariable regions. These hotspots are 
most intimately involved in the information of the antigen-binding site. In 
both VH and VL regions of the chain atleast three hypervariable regions/ 
hotspots are present. The infinite range of the antibody specificity of 
immunoglobins depends on the variability of the amino acid sequences at the 
'variable regions' of the H and L chains, which form the antigen combining 
sites (Paratope). 

2. Constant (c) region (or) Fc region (Fc = fragment of constant region) : 
The C region denotes constant region with unvarying amino acid sequence in 
the C or COOH terminal portion of the molecule. 

(Fab - Fragment of antigen binding site 

Fc - Fragment of constant region) 

Depending on the observable reaction produced on mixing with anti- 
gens, the antibodies are designated variously as agglutinins, 
precipitins and so on. Sera having high antibody levels following infection 
or immunization are called immune sera or anti sera. 

Transplantation immunology 

The replacement of a diseased organ by a transplant (healthy tissue 
or organ) is called transplantation. In the early 1940 Medawar explained 
the nature of graft (transplant) rejection while working with the burn patients 
of World War II. In his observations the following features were made clear. 
1 . graft of skin from one region of the body to another in the same patient 
was easily accepted, 2. grafts obtained from close relatives like brother or 
sister, were rejected 3. when a second graft was performed, by obtaining the 
tissue from the same donor, the rejection reaction occurred with greater 
intensity and speed. The graft or transplant leads to various complications in 
the host body. They are mediated by the host's immune response. Very often 

153 



the transplant gets rejected or may lead to graft verses host reaction or 
disease. Before discussing the nature and implications of this rejection 
phenomenon let us look into the terms involved in various types of grafts. 

Classification of grafts : The graft can be classified into four major types. 

1. Autograft : The tissue of the original donor is grafted back into the same 
donor. For example, skin graft from thigh to face in severely deformed case 
of burnt individuals (plastic surgery). 

2. Isograft : Graft between syngeneic individuals (ie., identical genetic 
constitutuion). For example, clones or identical twins. 

3. Allograft : (Homograft). Graft between allogenic individuals (ie., 
members of the same species but of different genetic constitution. For 
example, kidney transplanted from one human to another. 

4. Xenograft : (Heterograft). Graft between xenogenic individuals (ie., 
different genetic lineage). For example organ transplanted from pig to 
human, baboon to human. 

Genetic basis of organ transplants : 

Success of organ transplants (ie., Cornea, Kidney, Heart, Liver, Bone 
marrow) and skin grafts depends on a proper matching of histocompatibility 
antigens that occur in all cells of the body. Chromosome 6 of mouse contains 
a cluster of genes known as the major histocompatibility complex (MHC), 
which in humans is called human leukocyte antigen (HLA) complex. The 
alleles of HLA genes determine the histocompatibility ie., the compatability 
between donor and recipient tissues in transplants. 

Process of graft rejection : (Allograft) 

When the graft or tissue involves two genetically distinct members of 
the same species, graft rejection occurs because the antigens of the graft and 
host being different, the immune response of the host rejects the graft. The 
graft dies, decays and is eliminated from the host. The host also reacts to the 
graft and shows the following symptoms. 1. Skin rashes, 2. Fluid accumulation 
in spleen and enlargement (Splenomegaly), 3. Emaciation (becoming thin), 
4. Diarrhoea, 5. hepatomegaly, 6. Anaemia and general immune 

154 



suppression, 7. Damage in bile ducts, 8. Increased bilirubin synthesis etc. 
Both cell mediated and humoral immune responses follow in rejection. 
Sensitized T cells (lymphocytes), macrophages, plasma cells are all involved 
in the primary or first set rejection. In the secondary or second set reaction, 
B cells (B lymphocytes) and their antibodies are involved. In the cell 
mediated reaction substances such as interleukin 1 (IL-1), Interleukin - 2 
(IL-2) etc take part. The final lysis of the graft is achieved by lymphotoxins 
or TNF (Tumour necrosis factors) or proteolytic enzymes. 

In clinical fields, graft rejection is prevented by : 1 .Blood groups 
estimation (ABO and Rh) in the host, 2. Testing the presence of cytotoxic 
antibodies in the host serum, 3. Cross matching of tissues (Host Vs graft) 
prior to transplantation, 4. Giving immunosuppressive drugs like cyclosporin 
and steroids etc to the host, 5. Total lymphoid tissue irradiation etc. 

In recent years, the cloning technology promises to bring solution to 
the problems of graft or tissue rejection in transplantation surgery. By stem 
cell technology and cloning of cells, organ culture is feasible. Organs 
cultured from the same embryo or individual are safe and valuable for 
transplantation surgery. 

Immune system disorders 

The immune system is a multicomponent interactive system. It 
effectively protects the host from various infections. But an improper 
functioning of the immune system can cause discomfort, disease or even death. 
The improper functions fall into the following major groups : 
(1) hypersensitivity or allergy, (2) auto-immune diseases, and 
(3) immunodeficiency. 

(1) Hypersensitivity 

Allergies result from an inappropriate and excessive immune response 
to common antigens. Substances that cause allergies are called allergens ; 
they include dust, moulds, pollen, certain foods, and some medicines (such 
as penicillin). Allergy involves mainly IgE antibodies and histamine. Mast cells 
secrete the histamine. A common manifestation of allergy is asthma. Sometimes 
an allergen may cause a sudden, violent and fatal reaction in a sensititive 
individual ; this is called anaphylaxis. 

155 



(2) Autoimmune diseases 

Autoimmune diseases result when the immune system attacks and 
destroys "self cells and molecules. This condition can cause chronic and 
serious diseases. Examples of autoimmune diseases are insulin-dependent 
diabetes, multiple sclerosis, rheumatoid arthritis, etc. Multiple sclerosis is 
caused by antibodies that attack the myelin sheath of nerve cells. 

(3) Immunodeficiency diseases 

Immunodeficiency Diseases result from a defect in one or more 
components of the innate or adaptive immunity. Affected individuals are 
susceptible to diseases that normally would not bother most people. 
Immunodeficiency may result from gene mutations, infections, malnutrition 
or accidents. 1 . Severe combined immunodeficiency (SCID) results from 
one of many genetic defects; one such genetic defect leads to adenosine 
deaminase deficiency. SCID is characterized by a very low number of 
circulating thymocytes. Affected individuals usually die at an early age. 
2. AIDS (Acquired Immuno Deficiency Syndrome) is another example for 
immunodeficiency disease. It is caused by a retrovirus, known as human 
immunodeficiency virus (HIV). Retroviruses have RNA genomes that are 
replicated via DNA copies. HIV, selectively infects and kills T- helper cells. 
The depletion of T-helper cells weakens the acquired immune response and 
may even abolish it completely. The viral RNA genome is converted into 
DNA copy by the viral enzyme reverse transcriptase. The DNA copy of 
HIV becomes inserted into the human chromosome and replicates with the 
cell DNA. It may be transcribed to produce RNA copies of the viral genome. 
The RNA copies are packaged and liberated as virus particles. The infected 
cell is lysed in this process, and the released virus particles infect new T- 
helper cells. 



156 



4. MODERN GENETICS 

Introduction and Scope 

Genetics deals with various concepts and phenomena related to 
inheritance. Mendel's findings sowed the seeds for understanding the 
secrets of heredity and paved the way for further knowledge on genes and 
chromosomes. The post Mendelian period was remarkable in that many new 
concepts and hypotheses related to general genetics such as factor (gene) 
interactions, sex determination, linkage, sex linkage, crossing over, cytoplasmic 
inheritance, multiple allelism polygenic inheritance were added. The 
discovery of double helical DNA by Watson and Crick in 1953 has 
unraveled the secrets of gene functions. The voluminous works on 
Drosophila and prokaryotes like Escherichia coli opened up a new era of 
modern (molecular) genetics. In modern genetics, human genetics 
constitutes a part. It attempts to bring informations most important for 
understanding the genetics of man who is also a species like any other 
taxonomic species. Human genetics involves the identification of human 
chromosomes; genetic engineering prospects; genetic diseases and gene 
therapy; cloning devices; transgenic or genetically modified organisms etc. 
Towards this line, the modern genetics also deals with the human genome 
project; bioinformatics / biological data base and proteomics. 

Human Genetics - Karyotyping. 

Karyotyping is a technique through which the complete set of 
chromosomes are separated from a cell and the chromosomes are lined up in 
a karyogram. The term karyogram has now been replaced by another word 
called Idiogram referring to a diagrammatic representation of chromosomes. 

The karyological studies are usually made during mitosis, though the 
chromosome structure and details can also be best done in meiotic 
preparations. It is much easier to obtain and prepare suitable mitotic cells. 
Mitosis also reveals the replicated chromosomes viz., sister chromatids. 



157 



The diploid set of chromosomes in the eukaryotic cells has 
constant morphological (phenotypic) features such as number, size, shape. 
The chromosomes are identified by other features such as the 
secondary constriction, arm ratio, and banding pattern. The summation of all 
such characters, which identify a set of chromosomes is called 
karyotyping. 

Karyotyping involves the culture of foetal cells found in the 
amniotic fluid, in vitro, in a highly nutritive solution containing phytohaemag- 
glutinin. The foetal cells are cultured with colchicine. Colchicine stops 
mitosis at metaphase. When these cells are subjected to a hypotonic 
solution, the cells swell because the soluble salts are of lower concentration 
than in normal protoplasm. The water diffuses into the cell and separates the 
chromosomes. The scattered chromosomes are then placed on a slide, stained 
and photographed under a microscope. Individual chromosomes are then 
cut off from the photograph and marked as homologous pairs to form an 
idiogram. 

Karyotyping of Human chromosomes : 

I- A -| l-B-l _ c _, 

!! !! M !! " « ii 

ii II » ll ii » i! 



4 



c 



II !! ll ii || ■■ 

II II Ii ll if ii 

7 8 9 10 11 12 

13 14 15 16 17 18 

Jz— F — i | G 1 

■ ■ ■■ *w 

U II ac ii SB 

19 20 21 22 y 

Fig. 4.1. Karyotyping of human chromosomes - 
pairs of chromosomes during metaphase 



158 



The 23 pairs of chromosomes in human are classified into seven 
groups viz, A-G based on position of centromere. 

Group A : This group includes the largest chromosomes 1,2 and 3. These 
are metacentric with centromere found in center with two equal arms. 

Group B : This group represents chromosomes 4 and 5 which are 
submetacentric with two unequal arms. 

Group C : This is the largest group containing chromosomes 6,7,8,9, 10, 1 1 , 12 
and X. These are of medium size and submetacentric. The X chromosome 
resembles the chromosome 6 in this group. 

GroupD : These are medium sized chromosomes with nearly 
(acrocentric) terminal centromeres. The chromosomes 13,14 and 15 are kept 
in this group. 

Group E : It consists of chromosomes 16,17 and 18. They are shorter and 
meta or submetacentric. 

Group F : Shorter metacentric chromosomes 1 9 and 20 represent this group. 

Group G : This group comprises the very short acrocentric chromosomes 
21, 22 and Y belong to this category. 

Uses : 

1 . Karyotyping helps to identify the sex of individuals through amniocentesis. 

2. Genetic diseases in human beings can be detected by this 
technique. If a disease is detected, the medical councelling for termination of 
pregnancy and abortion of such foetus can be done. 

3. By characterizing the normal karyotype, the chromosomal 
abnormalities such as deletion, duplication, translocation, non-disjunctions 
and the consequent aneuploids could be detected. 

Genetic Engineering 
(Recombinant DNA Technology) 

All living organisms are endowed with specific genetic 
information. With advancement that progressed in genetical science, many 

159 



aspects of gene functions became obvious. The molecular functioning of genes 
revealed the central dogma that DNA in a eukaryotic cell undergoes tran- 
scription to synthesize RNA and the latter undergoes translation to 
produce protein (polypeptide). Even before the modern aspects of 
molecular genetics are discovered, the existence of mobile genetic elements 
(Transposons) were visualized by the geneticist Barbara Meclintock in her 
work on maize plant Zea mays in 1965. 

E. coli containing plasmids^f ' '" ' fy ^foreign DNA 

*U restriction enzyme 

plasmidsDNA ^tjb JL 

, restriction enzyme c .-."^pieces of foreign DNA 



plasmid (vector) DNAaf-*i§t DN A "gase^ 
plasmid free E.coE'^Vj ^introduced into the host 



=■-- ■ '«* sa>» 

~ clones of cells' 
Fig. 4.2. Genetic engineering - Recombinant DNA technology 

Genetic engineering deals with the manipulation of genes 
according to human will. A gene of known function can be transferred from 
its normal location into an entirely different cell or organism, via a suitable 
carrier or vector. The carrier may be a plasmid DNA segment of a 
bacterium or a virus. The gene transferred likewise starts functioning to 
synthesize the particular protein in the new environment. Thus, the fact that, 
a gene can function irrespective of its environment formed the basis for 
genetic engineering. 

Tools of Genetic Engineering : 

Genetic engineering which involves isolation of a gene segment from 
the whole genome, cloning of the gene into multiple copies and their 
expression needs several biological tools. Some of them are given below. 

160 



1 . Enzymes : a. Exonucleases, b. endonucleases, c. restriction endonucleases, 
d. SI enzymes to convert the cohesive ends of single stranded DNA 
fragments into blunt ends, e. DNA ligases, f. Alkaline phosphatase, 
g. Reverse transcriptase, h. DNA polymerase etc. 

2. Foreign DNA / Passenger DNA : It is a fragment of DNA molecule, 
which is to be enzymatically isolated and cloned. 

3. Cloning vectors : Vectors or vehicle DNA are those DNA that can carry 
a foreign DNA fragment when inserted into it. The vectors generally used 
are bacterial plasmids and bacteriophages. 

Plasmids : 

A plasmid is a circular DNA with about 200-300 nucleotides. It is 
present in bacterial cells alongside their main chromosomes. A plasmid 
sometimes can leave from one bacterial cell and enter another, through, 
conjugation and thereby transfer genetic traits to the recepient cell. The 
plasmid DNA inside a bacterium can replicate independently of the main 
DNA and can depart from main genome dragging a piece of main DNA 
along with it. It is called the bacterial DNA. A plasmid can sometimes fuse 
with the main DNA. Thus the plasmid seems to be an efficient gene exchanging 
vehicle which the nature has produced. 

Isolation of gene 

In recombinant DNA technology, restriction endonucleases cut the 
DNA double helix in very precise manner. They recognize specific base 
sequences on DNA. They cut each strand of DNA at a given place. These 
enzymes recognize specific DNA sequences which are called palindrome 
sequences. A palindrome refers to a base sequence that read the same on 
the two strands but in opposite directions. For example if the base sequence 
on one strand in GAATTC read in 5 '-3' direction, the sequence on the 
opposite (complementary) strand is CTTAAG read in 3 '-5' direction. There 
is a point of symmetry within the palindrome. In the example given this point 
is in the center between the AT/TA. 

5' GAATTC 3' 
3' CTTAAG 5' 

161 



Examples of Restriction enzymes :- 

The restriction enzymes cut the DNA molecule around the point of 
symmetry. The above palindrome sequence is recognized by the 
restriction enzyme derived from Escherechia coli, called EcoRl . It cuts the 
DNA molecule into discrete fragment with staggered cut ends. 

Recombinant DNA :- 

The foreign DNA fragment isolated is made to recombine with the 
plasmid DNA which is cleaved by the same restriction endonuclease. The 
recombination of the two DNAs is effected by the DNA ligase enzyme. The 
product formed is called recombinant plasmid or recombinant DNA. 

Molecular cloning :- 

The recombinant DNA must be introduced into a host cell, within 
which it may replicate freely. Escherechia coli has been employed as a 
suitable host to the above. Alongside, with the multiplication and growth of 
the bacterium in the medium, copies of rDNA are also produced. In 
molecular cloning, besides E.coli other microbes that have been employed 
include Bacillus subtilis, Strptomyces sp., Saccharomyces cerevisieae etc. 

When the rDNA copies are introduced into the host cells, (E. coli) a 
few thousand of rDNA pieces may enter the cells. These cells are called 
transformed cells. Each transformed cell grows a colony of its own in which 
every member is genetically alike. These colonies are then distinguished and 
recultured separately. 

From the recultured colonies, the recombinant DNA is extracted from 
lysed cells, purified and used. The first gene was cloned in 1973 by Hebert 
Bayer and Stanely cohen of Stanford University, California of USA. 

Application and Uses of Recombinant DNA Technology 

1. Genetic engineering/recombinant DNA technology has enabled the 
understanding of structure of eukaryotic genes and their components. 

2. Genetically engineered bacteria are employed to synthesize certain vital 

life saving drugs, hormones and antibiotics eg., Antiviral / anticancer interferons 

; human growth hormone (HGH) somatostatin, etc. 

162 



3. Through recombinant DNA technology, the gene types of plants are al- 
tered. New transgenic plants which are resistant to diseases and pest attack 
have been produced. 

4. Genetic defects in animals as well as human could be corrected through 
gene therapy. 

5. Genetically engineered bacteria are called superbugs. Superbugs can de- 
grade several aromatic hydrocarbons, at the same time. They are employed 
in clearing oil spills in the ocean. Thus these are used in pollution abatement. 
The super bug was produced first by an Indian researcher Anand 
Chakrabarthy in USA. He developed a strain of Pseudomona bacterium to 
clear up oil spills. The above superbug can destroy octanes, xylenes cam- 
phors and toluenes. 

DNA - Segmenting / Fragmenting 

DNA segmenting in genetic engineering refers to fragmenting of DNA 
and sequencing or mapping the DNA in terms of its nucleotide 
sequences. Chemical and enzymatic methods are available for the above. As 
a result the genie and non-compartments of DNA can be identified. 

In human beings, more than three hundred hereditary diseases have 
been indentified. All these diseases have genetic background. Gene 
mutations, chromosomal aberrations are the attributed reasons for the 
manifestation of such genetic diseases in man. Most of them are congenital in 
nature. 

Pedigree analysis : Unlike animals, controlled crosses can not be made in 
human beings. Hence human geneticists, resort to a scrutiny of 
established matings. The scrutiny of established matings to obtain 
information about the genetic characters / traits is called pedigree analysis. 

Pedigree chart : Pedigree chart defines the history of a character in a family. 
It is drawn up using certain standard symbols. It is also called as the Family 
tree. Pedigree chart helps to identify and visualize the course of genetic dis- 
eases in the progeny. This is especially true of diseases such as fibrosis and 
phenylketonuria (PKU). 



163 



Symbols commonly used in Pedigree Charts 



] - Male 
Q - Female 



n — o- Matm g 



n- 



o 




Monozygous twins 



£6 



- Parents and children 




Dizygous twins 



Popositus (first individual affected) 
■ft - Affected individulas 



I Q - Consanguine marriage | 

(£|) - Carrier for sex linked recessive 

Fig. 4.3. Symbols for pedigree chart 



Heterozygous for 



Affected 
Female 



(^J 1 [ | Heterozygous (^J 1 1 | F, 



Normal 



Affected 
Female 
Fig. 4.4. Pedigree chart for Polydactyly 



6 



Male 



( J Female 

^p Affected Heterozy 

164 



gous 



Genetic Diseases 

1. Sickle cell anaemia : 

Sickle cell anaemia is a genetic syndrome caused by an autosomal 

s s 
mutant allele Hbs. In homozygous condition (Hb Hb ), it causes the 

production of an abnormal haemoglobin called haemoglobin S. The 

normal haemolobin is designated as Hb (Hb Hb ). Sickle cell persons with 

the genotype HbsHbs suffer from a fatal haemolytic anaemia. The 

patient dies due to damaged heart, kidney, spleen and brain as a result of 

clogged blood vessels or vascular obstruction. Persons with heterozygous 

genotype Hb Hb are said to be carriers and they survive. 

2. Thalassemia : 

Thalassemia is an erythroblastic anaemia due to homozygous 
recessive gene expression in children. Two types of this disease viz., 
thalassemia major and thalassemia minor exist. The former is the severe form 
while the latter is its milder form. The homozygotes suffer from 
severe thalassemia while all heterozygotes suffer from milder thalassemia. 
The clinical manifestations of thalassemia include I) decrease in the bone 
marrow activity, ii) peripheral haemolysis, iii) splenomegaly (enlarged spleen) 
and hepatomegaly, (enlarged liver) etc. The thalassemic children die at the 
age of seventeen. 

3. Agammaglobulinemia : 

Agammaglobulinaemia is a recessive gene disease, wherein 
r-globulin synthesis fails to occur. In this disease, the patient shows a great 
deficiency or total absence of plasma cells and unusual lymph nodes with 
fewer lymphocytes than normal. The failure of antibody synthesis in this 
disease, makes the subjects more prone to viral and bacterial infections 
especially of the chest .This disease mostly affects boys. 

4. Albinism : 

It is an inherited disorder of melanin metabolism 
characterized by the absence of melanin in the skin, hairs and eyes. The 
clinical characteristics of this disease are the milk-white coloured skin and 
marked photophobia. Albinism is an inborn error metabolic disease, In this, 

165 



the genes by undergoing mutation do not produce particular enzymes, which 
take part in the metabolic pathways. The metabolism of one amino acid 
phenylalanine proceeds in chains of enzyme-mediated reactions. The change 
or absence of enzyme due to defective genes, results in physiological 
abnormalities. In albinism, complete lack of melanin pigment (a dark brown 
pigment) causes the albino to suffer. The incidence of albinism in human has 
been reported to be from 1 :5000 to 1 :25000. The albinism may be generalized 
albinism, localized albinism of the eye (ocular albinism) or partial albinism 
(skin and hair). The recessive genes 'aa' do not produce the tyrosinase 
enzyme, which converts DOPA (3,4 - dihydroxy phenyl alanine) into melanin 
in the melanocytes. 

5. Huntington's chorea : 

This is a fatal disease caused by an autosomal dominant gene in hu- 
man. The onset of the disease is between 35 and 40 years of age. It is 
characterized by uncontrolled jerking of the body due to involuntary 
twitching of voluntary muscles. It leads to progressive degeneration of the 
central nervous system accompanied by gradual mental and physical 
deterioration. Huntington's disease was the first completely dominant 
human genetic disease to come to light. The affected gene is located on chro- 
mosome 4. Other characteristics of this disease are deterioration of intellec- 
tual faculty, depression, occasional hallucination and delusions and other psy- 
chological problems. This disease is incurable. 

6. Severe Combined Immunodeficiency (SCID) : 

This is an extremely rare inherited disease affecting children. The gene 
for the disease called ADA (Adenine deaminase) is located on 
chromosome 20. The children suffering from the syndrome completely lack 
the immune defense mechanism against infection due to rapid death of all 
white blood cells. SCID is also called Bubble Boy Syndrome. The child is 
kept in a sterile bubble. Unless given bone marrow transplant, the child's life 
span is short lived. 

Human Genome Project (HGP) 

Human genome project involves the human genome programmes to 
understand the genetic composition and genetic instruction that make up a 

166 



human. The human genome is nothing but the DNA that resides in every 
human cell. The location and composition of 30,000 (thirty thousand) genes 
in human have been identified by sequencing the genome. It is known that the 
genes carry the information for the synthesis of various proteins. These pro- 
teins take up different profiles such as enzymes, hormones and antigens, which 
are responsible for various physiological and biochemical functions. The 
completion of the human genome project, by determining the DNA 
sequence of all the 23 pairs of chromosomes is a turning point and a break 
through in biology and medicine. 

Human gene bank / genome database 

Human gene bank or the genome database is the collection of 
sequenced genes and cataloging of them for future use. They represent the 
fundamental data. 

Proteomics 

Human genome analysis involves the analysis of proteins. Analysing 
different proteins and locating them in cells and identifying their respective 
genes, which encode them in the cells, represent the science of Proteomics. 
For identifying the proteins, the cells, mRNAs are probed. Researchers have 
identified about 60000 (Sixty thousand) different m-RNAs in human beings. 
From the mRNAs the respective genes/DNA are traced. The above said 
DNA is known as cDNA (Complementary DNA). 

In the human genome project many disease related genes have been 
mapped to specific chromosomal regions. 

Protein coding genes 

In the human genome project, proteins of different families which are 
involved in development and cellular processes such as neuronal 
function, homeostasis, immune function and cytoskeletal complexity have been 
identified. 



167 



Significance and Benefits of HGP 

1. The sequence of human genome will enable geneticists to cure the killer 
diseases like cancer. 

2. It may enable us to understand more about the diseases and thereby to 
design drugs. 

3. HGP aids in diagnosis of defective genes that cause disease. 

4. As HGP may serve as a tool to Eugenical concept, scientists can 
create superior, disease free human beings in future. 

5. It helps in somatic cell gene therapy and germ line gene therapy. 

Cloning 

Cloning is an experimental technique wherein, a group of 
genetically identical organisms is produced. Cloning of various 
animals was has become possible due to knowledge gained in the field of 
developmental biology and developmental genetics. It helped a lot, to 
understand the genetic control over differentiation of cells and the 
development of multicellular organisms. 

Differentiation : In the development of multicellular animals the zygote 
represents the progenitor cell of the future embryo. Multitudes of cells arise 
from mitotic divisions of the fertilized egg cell. These cells later become 
distinct cell types differing in form and function. This process is called 
differentiation. 

In the 1950s two embryologists R.Briggs and T.King developed a 
technique called nuclear transplantation. The nuclei from frog egg cells are 
taken out with a micropipette (enucleation) and replaced with nuclei taken 
from the cells of an embryo the same animal. The recipient cells developed 
into normal tadpoles and frogs with all the different cell types. The investigators, 
with the above technique produced a number of genetically identical 
individuals. Cells of early embryo which are capable of complete 
development and producing the whole organisms are said to be totipotent. 



168 



However, experiments by J. Gurdon revealed that nuclei from older 
embryos and tadpoles when transplanted to the enucleated egg cells 
affected the developmental potential. The older the individual from which the 
nuclei were taken, less the recipient egg cell was able to develop 
normally. His experiments also revealed that cells from different parts of the 
embryo differed in the degree of successful development attained after nuclear 
transplantation. It is learnt that cells of embryos at a later stage of 
development switch over from totipotent state to pluripotent state. The later 
gives rise to development of specific tissues or organs. 

Cloning of Sheep (Mechanism) : 




translocation 



genetic mother 
surrogate mother 



Fig. 4.5.Mechanism of cloning of sheep 



Dr. Ian Wilmut has produced a cloned sheep called Dolly by nuclear 
transplantation method. To produce cloned sheep he took the udder cell 
which is a somatic cell with diploid number of chromosomes. An egg cell 
was also removed from a donor sheep. The egg cell cannot grow into a new 
sheep on its own because it only has half a set of chromosomes(n). The 
body cell cannot grow into a new sheep on its own because it is not a 
reproductive cell. So udder cell nucleus(2n) was removed. Similarly the egg 
cell nucleus (n) was also removed. The nucleus of the somatic cell (Udder) 
was injected into the enucleated egg. The egg after the nuclear 

169 



transplantation comes to possess full set of chromosomes viz. the 2n 
diploid. The egg was then transplanted back into the uterus of the sheep 
from which it was removed. The egg also can be transplanted to a new 
surrogate mother for development. The egg cell grew and developed into a 
sheep (Dolly). This cloned sheep is genetically identical to the donor sheep, 
which donated the diploid nucleus of its somatic cell and not the sheep which 
donated the egg cell. 

Ethical Issues, Merits and Demerits of cloning :- 

1. Cloning of animals is considered as an unethical and unnatural 
technique by some people. 

2. It is feared that attempts to clone human may lead to the birth/production 
of wrong persons. 

3. Cloning cannot produce children like the children born to genetic mothers. 
Variations in traits are bound to appear. 

4. When organisms are created by cloning from somatic cells of the adult, 
the longevity of the new born, disease tolerance capacity are some criteria to 
be considered. Cloned animals have also developed diseases like arthritis. 

5. Cloning also leads to wastage of egg cells. In the cloning of Cat, 200 egg 
cells were used and 57 were implanted. Out of that only one cloned cat 
survived to birth. 

6. Cloned animals may have health problems. They may die at a much earlier 
age than the rest of the species. So cloned animals from 
somatic cells of adult, may have short life span. 

7. Among the benefits of cloning, special mention should be made 
regarding its role in biodiversity. Cloning will help to maintain biodiversity. It 
can bring back even the animals which have become extinct recently and 
safe guard all endangered species facing extinction. 

8. Though human cloning has its own ethical problems, the 
principle could be used to grow new organs from the cloned stem cells. Such 
organ culture may solve transplantation problems, such as tissue 



170 



incompatibility, tissue rejection, harmful immune reactions etc. Many human 
lives could be saved. 

Transgenic organisms 

Genetically Modified Organisms (GMOs) 

In genetic engineering, the methods of gene transfer lead to the 
production of transgenic animals and plants. These are called genetically 
modified organisms. Transgenism has been recognized as one of the thrust 
areas of biotechnology. 

Gene transfer Methods 

The uptake of genes by the cells in animals is called trans fection. 
The transfected cells are used for a variety of purposes such as 1. The 
production of chemicals and pharmaceutical drugs, 2. Study of structure and 
function of genes and 3. Production of transgenic animals of 
commercial value such as livestock animals and fishes. It is also called 
molecular farming. In transfection, fertilized eggs/embryos or the cultured 
cells are employed. 

Transfer of genes to Fertilized eggs or embryos 

The transfection of fertilized egg involves either the transfer of whole 
nuclei or whole chromosomes; or their fragments or the DNA 
segments. 

A. For the transfer of whole nuclei, the cells are treated with cytochalasin B 
and enucleated. The enucleated cells are incubated with the desired 
karyoplasts (nuclei) for induction in presence of polyethylene glycol (PEG). 

B. For transfer of whole chromosomes, metaphase cells are subjected to 
hypotonic lysis and individual chromosomes or fragments are isolated and 
then incubated with whole cells/eggs for transfection. 

C. Microinjection of DNA segments : In this the fertilized eggs are injected 
with DNA segments for integration. DNA integrated eggs are then used for 
getting transgenic animals. 



171 



D. Transfer of genes to cultured cells : In this stem cells are used. The stem 
cells are undifferentiated precursor cells. In these cultured cells, the gene can 
be delivered through vectors like retroviruses or directly by techniques such 
as microinjection using particle gun, electroporation or by the use of 
liposomes. 

Transgenic animals have been produced in a variety of animals such 
as mice, rabbits, sheeps, pigs, goats, cows, fishes etc. 

Uses: 

1 . Transgenic animals are more efficient than their normal counterpart in feed 
assimilation. 

2. They exhibit faster growth and hence achieve the marketable size sooner. 

3. Meat quality is good. 

4. They are resistant to certain diseases. 

5. They serve as bioreactors for obtaining valuable recombinant 
proteins and pharmaceuticals from their milk or urine or blood. 

Gene therapy 

The fact that genes can be cloned to several thousand copies through 
genetic engineering has given rise to an entirely novel model of therapeutic 
device viz., Gene therapy. Gene therapy involves the replacement of 
corrective genes in place of defective genes in human. There are two types 
of gene therapy. They are 1). Somatic cell gene therapy and 2). Germ line 
cell gene therapy. Both may be employed for treating the inherited diseases. 
In somatic cell gene therapy the patient's cells are taken from blood or 
bone marrow, or skin and brain, treated through genetic engineering and 
then replaced to the patient. Somatic cells are non-reproductive cells. These 
cells and their genes when corrected, the genetic changes will not be inherited 
to their children. On the other hand, this type of treatment could cure diseases 
caused by single gene mutations. In this therapy, retroviruses are employed 
as carriers of the genes. Their genetic material, RNA is copied into DNA. To 
produce effective vectors certain essential genes are spliced out from the 



172 



viruses. This will render the virus harmless and allow space for the therapeutic 
genes to be inserted. Hundreds of millions of copies of the genes are needed 
for somatic cell gene therapy. To carry them, the vectors should also be 
multiplied in equal numbers. Experimentally, such enormous copies of virus 
vectors are made using helper virus. The integrated vector and the cloned 
gene is used in somatic cell gene therapy. Somatic cell gene therapy has been 
successful in animals, so far. 

Germ line cell gene therapy 

The gene therapy is extended to reproductive or germ line cells in 
order to prevent the genetic defects being inherited to children. The 
technique has been shown to work positively in animals. In this, DNA is 
injected into the nuclei of single celled embryos of cows, mice and sheep. 
The DNA may get integrated into the chromosomes. The intergrated DNA, 
ie., the new genes can direct the synthesis of new proteins into animals which 
develop from these embryos. Germ line therapy has already been incor- 
porated developed in human embryos. Genes are inherited likewise 
through retroviral vectors into human germ cells. Germ line therapy in 
human is feasible, at any time, since eggs, sperms and single celled 
embryos can be collected and stored by deep freezing using liquid nitrogen. 
In vitro fertilization also may favour the above therapy. However, the therapy 
is still underway. 

Bioinformatics 

Definition : 

Bioinformatics deals with the creation and maintenance of 
databases of biological information such as the nucleic acid, gene sequences 
and protein sequences. It has its own applications in gene therapy, 
diagnostics, drug designing, crop improvement, biochemical processes etc. 
It involves the data analysis or creation of electronic databases on genomes 
and protein molecules. 

History of Bioinformatics 

From the beginning of the post Mendelian's period, genetic principles 
propounded by various geneticists have revealed the functional behaviour of 

173 



discrete hereditary particles called the genes, in the expression of various 
morphological (pheno typical) and biochemical traits of organisms. During 
the last three decades, the advancement in molecular biology, the invention 
of computers, ultra developments in scientific methodologies and introduction 
of instrumentation at nano level, have paved the way for the origin of 
bioinformatics. 

The preliminary discoveries such as the amino acid sequence of 
bovine insulin (1950s), nucleic acid sequence of yeast alaine tRNA with 77 
bases (1960s); X-ray crystallographic structure of protein, formed the basis 
and original databases for data entries and file making. With further 
advancements made in computational methods , empolying rapid search 
algorithms (BLAST) with hundreds of command options and input formats, 
the birth of bioinformatical science has been made. 

Applications 

Bioinformatics is a synergistic study of both biotechnology and 
information technology. In biotechnology living organisms of micro level and 
macro level organizations are employed, and manipulated towards 
harvesting beneficial products to human. In recent years Biotechnology is 
turning into an industrial science through genetic engineering. 

Genetic engineering helps the scientists to incorporate a single gene 
into an organism, and synthesize the desirable product without affecting other 
genes and their functions. In this way the biological systems or the microbial 
systems are manipulated 

Scope of Genetic Engineering 

i. To manufacture drugs and other life saving bioproducts such as insulin, 
growth hormones, interferons, cytokines and monoclonal antibodies. 

ii. For environmental management to reduce or abate the pollution load in 
soil or water. 

iii. In waste recycling to increase productivity. 

iv. In plant breeding by the incorporation of useful genes (nif genes = nitrogen 
fixing genes). 

174 



v. In bringing pest resistance in agriculture crops. 

vi. And in treatment of diseases by way of gene therapy etc. 

Such genetic engineering and biotechnological processes involve 
knowledge of enormous number of genes, their cooling and thier protein 
sequences. Computers and newly evolved software packages are utilised 
for these purposes. Thus biological studies are provided with a support from 
electronic computers. This new integrated field constitutes Bioinformatics. 

Scope of Bioinformatics 

1 . Bioinformatics helps to create an electronic database on genomes and 
protein sequences from single celled organisms to multicellular organisms. 

2. It provides techniques by which three-dimensional models of biomolecules 
could be understood along with their structure and function. 

3. It integrates mathematical, statistical and computational methods to analyse 
biological, biochemical and biophysical data. 

4. Bioinformatics deals with methods for starting, retrieving and 
analysing biological data such as nuclei acid (DNA/RNA) and protein 
sequences, structure, functions pathways and genetic interactions. 

5. The computational methods in bioinformatics extend information for probing 
not only at genome level or protein level but up to whole organism level, or 
ecosystem level of organization. 

6. It provides genome level data for understanding normal biological 
processes and explains the malfunctioning of genes leading to diagnosing of 
diseases and designing of new drugs. 

Definition of Database : 

'Creating' database means a coherent collection of data with 
inherent meaning, used for future application. Database is a general 
repository of voluminous information or records to be processed by a 
programme. 

Databases are broadly classified as generalized databases and 
specialized databases. Structural organisation of DNA, protein, 

175 



carbohydrates are included under generalized databases. Databases of 
Expressed Sequence Tags (ESTs), Genome Survey Sequences (GSS), Single 
Nucleotide Polymorphisms (SNPs) sequence Tagged sites (STSs). RNA 
databases are included under specialized data bases. 

Generalized databases contain sequence database and structure 
databases. 

a. Sequence databases are the sequence records of either nucleotides 
or amino acids. The former is the nucleic acid databases and the latter are 
the protein sequence databases. 

b. Structure databases are the individual records of macromolecular 
structures. The nucleic acid databases are again classified into primary 
databases and secondary databases. 

Primary databases contain the data in their original form taken as 
such from the source eg., Genebank (NCBI/USA) Protein, SWISS-PROT 
(Switzerland), Protein 3D structure etc. 

Secondary databases also called as value added databases contain 
annotated data and information eg., OMIN - Online Mendelian Inheritance 
in Man. GDB - Genome Database - Human. 

Nucleic acid sequence databases 

European Molecular Biology Laboratory (EMBL) ; National 
Centre for Biotechnology Information (NCBI) and DNA data bank of Japan 
(DDBJ) are the three premier institutes considered as the authorities in the 
nucleotide sequence databases. They can be reached at 

www.ebi.ac.uk/embl (for EMBL) 
www.ncbi.nlm.nih.gov/genbank (NCBI) 
www.ddbj.nig.ac.jp (DDBJ) 

Protein sequence databases :- 

The protein sequence databases elucidate the high level 
annotations such as the description of the protein functions ; their domain 
structure (configuration), amino acid sequence, post-translational 

176 



modifications, variants etc. SWISS-PROT groups at SIB (Swiss Institute of 
Bioinformatics) and EBI (European Bioinformatics Institue) have 
developed the protein sequence databases. SWISS-PROT is revealed at 
http://www.expasy.ch/sprot-top.html. 



"a ~-l l . f m'. I""-.™!". 1 It^K 1^- 
















_J R1 rOl 

3JL. F*.'l_-i"l K _ nL- 


E __i_"i 


3 




in 




[ i.v. .-.■ 


■■1-,.T-"-ll 

-' ft Li ■ V 


j^i-.^laji ■■. . :iliii— JT-ir.Hr. 












J 






[_}[■■ I ;.'■• jj i_\n} ij'[j\[* yf J u LJ U r ) 



fliA.-.iVh O T| i ■■■-ill ih i-f IMn 



IVilii.Ni LiirJllili:-! jiJIIr.-; 






U-L-J ^H? -|| 



1 




L-UbUpdU*? 

fcHJIHMfflBH 



abour DDBJ 

:r- i: 

L'U'SJ Lui ":^:lL.ij:.i-.'Illjj ul life LI.^U.I-.'ll.i.L.'J'.-Lt-.- lJ: 
;*:_u *■_::*■ i\?l?b?sz Jits. U?Jb >r?. - _joc ^Jh 33XTii-H- hk 
1"I"."." L -T'" 1 "-T _ n^snk 

JJNA y_q.-.iu;j : jl-;k-Is ui^azisii-i. _ --^Juli^ii iil.m v -Jb _ Jlv UitE. 
: rtw-. - "ji J jjSucal j."i7.::liyj itjc \x:s j _i'. r ii.aJt It .n >f ■dcI'. 1 Kc 
-•BSBifXSi .n Lf: "j*.n::5 ju: aJ;: Kalia !!■=■: tea. 1 : _n £*-i:r.i_ T^c 

:^n jj-::h :■!::■ >.i :. >■> ■: xt-KsJK. a i:-:i - ir-y - i H>in :-M iriin - *■ n i'- 



.-tfrJlKlJfLLfcJ 
-ir* I'.'iTi'. Inn .-!li 



EL-'y^b.-_-y;H 

.■■.i--i.'. I'.gi'wj": 
.H _ "■ i l i'.-.-'.'ji 1 . uT ji," 
.■y.'l'.a. UvULUV 



d 



jflS-l.nl | |] -^ 4f X? ^ S( J|*JI]I)IIJ UnTw^ni^-Mi 



Fig. 4.6.Home page of DDBJ 



Genome sequencing : 



The genome of an organism can be split up into different sized 
molecules by a technique called electrophoresis. When DNA of an organism 
is subjected to electrophoresis they migrate towards the positive electrode 
because DNA is a negatively charged molecule. Smaller DNA fragments 
move faster than longer ones. By comparing the distances that the DNA 
fragments migrate, their number of bases could be distinguished. The 
sequence of bases in the DNA fragments can be identified by chemical / 
biochemical methods. Nowadays automated sequencing machines called 
sequenators are developed to read hundreds of bases in the DNA. The 
DNA sequence data are then stored in a computer accessible form. 



177 



DNA library : 

A DNA library is a collection of DNA fragments, which contains all 
the sequences of a single organism. 

cDNA library (Complementary DNA) :- 

In cDNA copies of messenger RNA are made by using reverse 
transcriptase enzymes. The cDNA libraries are smaller than genomic 
libraries and contain only DNA molecules for genes. 

In the representation of either the nucleotides or the proteins, IUB/ 
IUPAC standards are followed. The accepted amino acid codes for proteins 
are given below. 



A-Alanine 


B-aspartate / asparagines 


C-Cystine 


D-Aspartate 


E-Glutamate 


F-Phenylalanine 


G-Glycine 


H-Histidine 


I-Isoleucine 


M-Methionine 


K-Lysine 


N-asparagine 


P-Proline 


Q-Glutamine 


R-Arginine 


S- Serine 


T- Threonine 


Z-Glutamate/glutamine X-any 
— gap of indeterminate length 


*-Translation 


stop 



The nucleic acid codes as follows (FASTA format) 



A-adenosine B-GTC C-cytidine D-GATG-guanosine 

R- Purines (guanine, adenine) T- Thymidine 

Y- Pyrimidines (thymidine, cytosine) U-Uridine H - ACT 

V-GCA N-AGCT B-GTC D-GAT 

— gap of indeterminate length. 



To specialize in bioinformatics, knowledge of both biology and 
information computer technology is required. A biologist needs to know 
programming, optimization (code) and cluster analysis, as they are 
bioinformatics methods. The biologists should also be familiar with key 
algorithms (set of steps). The languages, which help in bioinformatics, are C, 
C++, JAVA, FORTRAN, LINUX, UNIX etc. Besides knowledge of 
ORACLE database and Sybase are essential. On the mathematical part 
knowledge of calculus and statistical techniques are needed. Knowledge of 
CGI (common gateway interface) scripts is also needed. With the above, a 
bioinformaticist could collect, organize, search and analyze the biological 
data viz., the nucleic acids and protein sequences. 

178 



Uses of bio informatics 

1. It helps to understand gene structure and protein synthesis. 

2. It helps to know more about the diseases. 

3. It helps to understand more about the fundamental biology and the thread 
of life,- the DNA. 

4.. It paves the way for the medical and bio engineering applications. 

5. It helps to apply the biophysical and biotechnologicl principles to 
biological studies. In turn, it will help to design new drugs and new chemical 
compounds to be used in health and environmental management respectively. 

Protein structure 

Protein are linear chains molecules made up of units called amino 
acids. Approxoimately twenty different amino acids make up a protein chain. 
They are called polypeptide chains as they often contain a few to several 
hundred amino acids linked with each other by peptide bonds. Several 
polypeptide chains form subunits for a large protein. For example the 
haemoglobin consists of four subunits (Two alpha and two beta chains) each 
harbouring haeme, an iron containing molecule. The peptide bond between 
amino acids is fairly flexible. As a result, oligopeptide and polypeptide chains 
fold to a convoluted shapes. Every protein folds in a particular way to form 
a distinctive configuration for its specific function. The protein configuration 
is made primarily by the amino acids side chains. Some amino acid side 
chains are electrically charged (positive or negative). Others called polar 
molecules or neutral and strongly attract the electrons . A third group of amino 
acids are said to have non-polar or hydrophobic side chains. Thus proteins 
fold up in such a way that non-polar-hydrophobic groups remain buried 
inside the molecule and the polar and charged groups remain outside. 

The sequential and linear arrangement of amino acids in a 
polypeptide represents its primary structure. The folding of protein chain to 
form recognizable modules such as alpha helix and beta sheets 
represents its secondary structure . The three dimensional shape of a 
polypeptide is called its tertiary structure. Alpha helices and beta sheets 
provide further stability to protein structure. 

179 



The proteins synthesized inside a cell undergo the above mentioned 
configurational changes to attain stable structures. Otherwise, they will be 
digested or destroyed by the cellular proteolytic enzymes. The proteins take 
up different profiles as structural and functional proteins such as enzymes 
and hormones etc. 

In proteomics, the amino acid sequences are read by automated 
sequenators and stored in computers as internationally available databases. 
The information regarding three-dimensional structure of protein is stored in 
another computerized database called Protein Data Bank. Only three 
dimensional forms are used to define protein structure. 

Protein Model 

In proteomics, to delineate information about a protein at atomic and 
molecular levels, models are constructed. X-ray crystallography can give a 
skeleton model of a protein from its results on its atomic details. With atomic 
data, computers nowadays generate graphic images of the molecules on 
high-resolution screen. Computer modeling of protein began as early as 1970. 
The computer-generated models depict not only the properties of amino 
acids in a protein but also help to understand the protein function. One of the 
computer graphic models is the "Glowing coal" model. 

Uses : 

1. Protein structure helps in understanding biomolecular arrangement in 
tissue or cellular architecture. 

2. Protein structures, protein models and computer aided graphic 
models help to understand biological reactions mediated by enzymes 
(proteins). 

3. Graphic models provided by computers are valuable to predict which 
fragments of a medically important protein can be used to design drugs and 
vaccines. 

4. Proteomics also helps in chemical industries to manufacture drugs, various 
chemical compounds and enzymes. 



180 



5. ENVIRONMENTAL SCIENCE 

Environment literally means the surroundings of an object. 
Environmental science or ecology can be defined as the study of organisms 
in relation to their surrounding. Ecology is one of the most popular areas in 
biology. Mankind is greatly interested in ecology in view of the problems of 
overpopulation, environmental pollution, human survival, pest control and 
conservation of natural resources. The solution to all these problems involve 
ecological principles. Hence knowledge of environmental science is neces- 
sary for the survival of human race. 

Human population and explosion - Issues 

The world population was probably only a few million people before 
the invention of agriculture and the domestication of animals. The following 
table shows the alarming rate at which population has increased. 

World population growth 



Date 


Population 


5000 B.C. 


50 million 


800 B.C 


100 million 


200 B.C. 


200 million 


A.D. 1200 


400 million 


A.D. 1700 


800 million 


A.D. 1900 


1600 million 


A.D. 1965 


3200 million 


A.D. 1990 


5300 million 


A.D. 2000 

- 


6100 million 



181 



It has been calculated that the human population is growing at a rate 
of 90 million per year. At this rate the population would reach 12.5 billion 
by the year 2050. If the population keeps growing at this rate, after a few 
decades it will perhaps be too large for to be supported by the limited 
resources available on the earth. The rapid growth will affect living 
standards, resource use and the environment all over the world. 




IWl 



™ :w» 



I9?D I Mil 

years 
Fig.5.1. Total World population 1950 - 2000 



Demography 



Thomas Malthus studied the nature of population growth. He claimed 
that population was increasing faster than food production and feared global 
starvation. He proposed that, Population grows geometrically (1, 2, 4, 8) 
rather than arithmetically (1,2,3,4). The field of collecting, compiling and 
presenting information about population is called demography, and the people 
engaged in this work are named as demographers. 



Malthus and population growth 

In 1798, the English economist Thomas Malthus realized that while the 
human population was embarked on an exponential growth the 
agricultural production remain limited. He forecasted that massive 
famines would occur in the early 1800's. Malthus foresaw a world, headed 
toward calamity if something was not done to control the population 
increase. Contrary to his predictions, technological innovations have 
enabled enough agricultural production to the rapidly growing human 
population. 



182 



Population Dynamics 

A Population is a group of interbreeding organisms in a specific 
region. It is analysed in terms of its variability, density and stability along with 
environmental and other processes and circumstances that affect these 
characteristics. Thus the nature of a given population is determined based 
on birth and death rates, the distribution of ages and sexes, behavioral 
patterns, food supplies, other environmental features and migration. Fertility 
and birth rates, mortality and death rates helps us to assess the population 
growth rates. A dynamic population possess a stable life span and life 
expectancy. 

Uneven distribution of population 

Declining mortality and not the rising fertility is the primary cause for 
population growth during the past three hundred years. Population growth 
and its variation among nations is not uniform. Some regions of the world are 
over populated while others are literally uninhabited. The distribution of 
population is influenced by a number of physical and economic factors. The 
ecumen areas of the world with a congenial climate and fertile soils are 
highly favourable for human occupancy. Areas of harsh climate - too hot, 
too cold, too humid or too dry, rugged relief and low in resources are the 
non-ecumen areas. These are the areas where the natural environment is 
not conducive for human occupancy. 

Demographic statistics : Terminologies 

Fertility is the actual production of offspring. 

Birthrate is the number of births in a year per thousand persons. 

The total fertility rate is the number of children born to an 
average woman in a population during her entire reproductive life. 

The Zero Population Growth Rate (ZPG) is the number of births 
by which people are just replacing themselves. 

Mortality or death rates is the number of deaths per thousand 
persons in any given year. 



183 



Growth rates 

Death rate subtracted from birthrate gives the natural increase of a 
population. 

The total growth rate includes immigration and emigration, as well 
as births and deaths. 

Life span and Life expectancy 

Life span is the oldest age to which a species is known to survive. 

Life expectancy is the average age that a newborn infant can expect 
to attain in any given society. 

Population Explosion 

The rapid and dramatic rise in world population has occurred over 
the last few hundred years. The world's population increased from 1.65 
billion in 1900 to 3.02 billion in 1960 and reached 6. 1 billion in 2000. Thus 
the size of the population nearly quadrupled in the span of 100 years, a 
historically unprecedented rate of increase. This sudden acceleration of 
population is called as Population Explosion or Population Bomb or 
Population Trap. 



Regions with majority of world population 

The major regions of population concentration are the East Asian 
Region, South Asian Region and West European Region. 

The East Asian Regions : The largest populated areas. It includes 
countries like China, Korea, Vietnam, Cambodia, Japan and Indonesia 
with one fourth of the total population of the world. 

The South Asian Regions : The countries with second largest 
population concentration. India, Bangladesh, Myanmar, Pakistan and 
Srilanka are the South Asian countries accounting for 20% of the global 
population. 

The West European Region : has the third largest population 
concentration. European countries, Mediterranean and Arabian 
countries and British islands are the examples. 



184 



Reasons for the Explosion 

The main reason for slow and fluctuating population growth prior to 
early 1800's was the prevalence of diseases such as small pox, diphtheria, 
measles and scarlet fever. In addition, epidemics of diseases such as typhoid 
fever, cholera and plague eliminated large number of adults. Famines also 
were not unusual. Biologically speaking, prior to 1 80s the population was 
essentially in a dynamic balance with natural enemies and other aspects of 
environmental resistance. High reproductive rates were largely balanced by 
high mortality. 

Since the 19th centuary 

• discoveries of vaccination provides protections to many of the infectious 
agents 

• discovery of antibiotics is a major breakthrough in the medical history, 

• improvements in agricultural techniques, 

• improvements in the nutrition and 

• better sanitation and personal hygiene 

brought about spectacular reductions in mortality, especially among infants 
and children. The birth rate has remained high. So the human 
population entered into exponential growth, as they were freed from natural 
enemies and other environmental restraints. 

Growing Population and Environmental impacts 

Increasing numbers of people put increasing demands on the 
environment, both through demands for resources and through production of 
wastes. Most of the human population survived through subsistence 
agriculture to meet their needs. After the modern medicines and industrial 
revolution, the death rate plummeted and population growth increased. What 
are the impacts of rapid growth on a population that is largely engaged in 
subsistence agriculture? Five basic alternatives are being played out to 
various degrees, 

• people can subdivide farms among the children or intensify cultivation of 
existing land to increase production per unit area. 

185 



• open up new land to farm. 

• move to cities and seek employment. 

• engage in illicit activities for income. 

• emigrate to other countries legally. 

The rapid population growth especially affects women and children. 
Increasing the average wealth of a population affects the environment both 
positively and negatively. 



Over cultivation 
soil erosion 
Depletion of fertility 



Siltation of rivers 
Loss of fisheries 
Flooding 



Over fishing 
Depletion of 
marine stocks 



Poaching of wildlife 
drugs consumption 
other illegal 
activities 



Population Explosion 

Farms subdivided into 
small plots, no longer abley 
yto support families 



Move to cities 

Squalor 

Disease 



Antibiotic resistant 
strains of tuberculosis, 
malaria, pneumonia 
STDs 



^y. 



Brings new land 
into cultivation 
•^ Deforestation, Drain 
wetlands irrigation 



Depletion of water 
resources, loss of 
fisheries 



Migration Environmental 
•efugies. Immigration 
pressure on World 



_^k. 



Wild life extinction 
loss of biodiversity 
global climate change 



Consequences for 



the 



World 



Fig. 5.2. Consequences of Population explosion in developing nations 



186 



Global warming : Green house effect 



V-o 





3. Breakdown products 
destroy Ozone 

m 

c-o 



2. Sunlight breaks down 
CFC's in the stratosphere 



( ') 






V 



/ 



1. Factories and homes 
spew out CFC's. 



°0°l 



4. Scientists send 
up balloons to see 
where all the 
ozone's gone. 

Aft 



Fig. 5.3. Destruction of Ozone layer 

Global warming refers to an average increase in the earth's 
temperature, which in turn causes changes in climate. During the past 4.65 
billion years of its history, earth has warmed many times. But at present it is 
facing a rapid warming mainly due to human activities. The average 
temperature of earth is about 59°F (15°C). During the last century this 
average has risen by about 1°F. By the year 2100, it is believed that the rise 
would be between 2.5 and 10.4°F. This will cause dramatic changes such as 
rise in sea level, changes in rainfall patterns, wide range of impacts on plants, 
wildlife and humans. 

Green house gases and Green house effect :- 

The trapping of energy from the sun by certain gases in the 
atmosphere leading to the rise in earth's temperature is known as Green 
house effect. Hence these gases are known as green house gases. Some 
gases such as water vapour, carbon dioxide, nitrous oxide and methane act 
as the trap. These gases absorb and reflect infra-red waves radiated by earth. 
By doing so, these gases conserve heat as the glass in a green house does. 



187 



Normally all life on earth depends on this green house effect. If it 
does not exist, earth would be cooled, and ice would cover earth from pole 
to pole. But if the greenhouse effect becomes strong it could make the earth 
warmer than usual. Even a little extra warming may cause problems for 
humans, plants and animals. 

Types of Greenhouse Gases :- 

In the environment, greenhouse gases occur (i) naturally or (ii) from 
human activities. 

The most abundant greenhouse gas is carbon dioxide. It reaches 
the atmosphere due to volcanic eruptions, respiration of animals, burning 
and decay of organic matter such as plants. Normally carbon-dioxide is 
removed by the plants by photosynthesis. Carbon-dioxide is also absorbed 
into ocean water. But humans by their activities increase the release of 
carbon dioxide into the atmosphere . Such activities include burning of fossil 
fuels, solid wastes, wood and wood products to drive vehicles, generate 
electricity etc. At the same time due to deforestation, the number of trees 
available to absorb carbon-dioxide through photosynthesis has been greatly 
reduced. 

Human activities have caused carbon-dioxide to be 
released to the atmosphere at rates much faster than that at which earth's 
natural processes can recycle this gas. There were about 281 molecules of 
carbon-dioxide per million molecules of air (i.e., parts per million or ppm) in 
1750. Today atmospheric carbon-dioxide concentrations are 368 ppm, a 
31% increase. 

Methane traps 20 times more heat than carbon-dioxide. It is 
emitted during the production and transport of coal, natural gas and oil. It is 
also emitted from rotting organic waste in sand fills, by the cows as a by 
product of digestion. Since 1750, the amount of methane in the atmosphere 
has more than doubled. 

Nitrous Oxide traps 300 times more heat than carbon-dioxide, 
burning fossil fuels and ploughing farm soils releases nitrous oxide. Since 
1750 its level increased by 17%. Hydrocarbons formed from the manufac- 
ture of foams, coolants such as chlorofluorocarbons used in refrigerators 
are the other gases responsible for global warming. 

188 



In 2000, scientists discovered an alarming increase in the level of a 
new gas called trifluoromethyl sulphur penta fluoride. Eventhough the 
gas is rare, it traps more effectively than all other greenhouse gases. The 
saddest part of it is that the industrial source of the gas is not yet 
identified. 

Effects of Global warming :- 

1 . Due to the warming of oceans, sea level will rise. Glacier ice will also melt, 
causing further rise in sea level. Asa result in the 2 1 st century sea level will 
rise from 9 to 88 cm. Such a rise will submerge many parts of countries. 

2. Seasons will be longer in some areas. 

3. The warmed world will be generally more humid and greater humidity will 
increases the rainfall. 

4. Storms are expected to be more frequent and intense. 

5. Some regions of the world would become dry. 

6. Wind blows will be harder and in different patterns. Hurricane would be 
more severer. 

7. Weather patterns would be less prediclable and more extreme. 

8. Crops and forests may be affected by more insects and plant 
diseases. 

9. Animals and plants will find it difficult to adjust to the changed 
environment. Animals will tend to migrate toward the poles and toward higher 
elevations. 

10. Some types of forests may disappear. 

11. More people will get sick or die from heat stress. 

12. Tropical diseases such as malaria, dengue fever, yellow fever and 
encephalitis will spread to other parts of the world. 

Efforts to control Global warming: - 

Two major ways are there to control global warming: 1 . to keep the 
carbon-dioxide out of the atmosphere by storing the gas or its carbon 
component somewhere else, a strategy called carbon sequestration. 
2. to reduce the production of green house gases. 

189 



Carbon sequestration :- 

The simple technique is to preserve trees and plants more. Trees, 
take up carbon-dioxide, break it down in photosynthesis, and store carbon 
in new wood. It need massive reforestation. Carbon-dioxide can also be 
sequestrated directly into deep ocean water or into oil wells or some aquifer 
form which it cannot escape. 

Usage of alternate fuels such as nuclear energy, solar power, wind 
power and hydrogen fuel cells which emit no greenhouse gases are being 
considered. 

Ozone layer depletion 

Ozone is a form of oxygen (O3). In the stratosphere (ozonosphere), 
ozone blocks out the sun's ultraviolet rays and is a lifesaver. 

Ozone as a natural sun block 

The electromagnetic radiation emitted from the sun includes 
ultraviolet radiation, which is potentially harmful to most living things since it 
can damage DNA. The ozone layer screens out the sun's harmful 
ultraviolet radiation. Even 1 % reduction in the amount of ozone in the upper 
stratosphere causes a measurable increase in the ultraviolet 
radiation that reaches the earth surface. If there was no ozone at all, the 
amount of ultraviolet radiation reaching us would be catastrophically high. 
All living things would suffer radiation burns, unless they were underground, 
or in the sea. 

In the stratosphere, small amount of ozone are constantly being made 
by the action of sunlight on oxygen. At the sametime, ozone is being broken 
down by natural processes. The total amount of ozone usually stays constant 
because its formation and destruction occur at about the same rate. But 
unfortunately human activity has recently changed that natural balance. Some 
manufactured substances such as chloroflurocarbons and 
hydrochloroflurocarbons can destroy stratosphere ozone much faster than it 
is formed. 

190 



Ozone hole: 

Ozone loss was first detected in the stratosphere over the Antarctic. 
The part of the atmosphere where ozone is most depleted is referred as 
"Ozone hole" but it is not a real hole just a vast region of the upper 
atmosphere where there is less ozone than elsewhere. 




Fig. 5.4. Ozone hole 

Ozone-poor air can spread out from the Polar Regions and move 
above other areas. In addition, direct ozone less elsewhere is slowly 
increasing. 

Ozone-poor air can spread out from the Polar regions and move 
above other areas. In addition, direct ozone depleted are is also slowly 
increasing. 

Reasons for the Antarctic Ozone hole: 

Scientific observations prove that the ozone hole formed over 
Antarctic is due to compounds of chlorine and bromine formed in the 
atmosphere. Nearly all of the chlorine and half of the bromine in the 
stratosphere comes from human activities, the chlorofluocarbons released 
due to human activities transported up into the upper stratosphere. 

The most common Ozone depleting substances (ODS) are 
chloroflurocarbons (CFC) or freon gases, bromine compounds on halons, 
nitrogen oxides and methyl bromide. These compounds are liberally released 
from air-conditioners, freezers, foam insulations, aerosol products, industrial 
solevents, fire extinguishers and pesticides. 

191 



Effect of Ozone depletions: 



If the ozone is depleted more ultraviolet radiations (especially 
ultraviolet B (UVB) will reach the earths surface. 

Effect on plants:- will affect crop yield and forest productivity. 

Effect on animals:- will cause damage to fish larvae and other small 
animals 

Effect on human health:- Results in non-melanoma skin cancer and 
melanoma, acute erythem a (sun burn), ocular abnormalities, cataract, affect 
immune responses. 

The general effect of ozone depletion is summed up in the following chart 

CFC's 



Global Warming 



T 




Ozone depletion 
stratosphere 





Plankton 




/ 




\quatic 
jcosysterm 
'ish stocks 





Terrestrial 
ecosystems 
crop failure 



Increased 
ultraviolet - B 



Malnutrition 



Ozone Increase 
troposphere 



Flooding sanitation, 
Vector-born diseases 
Temperature 
extremes 



Respiratory 
ailments 



192 



Preventing ozone depletion: 

1. CFC's (Chloro Fluro Carbons) should be replaced by HCFC's (Hydro 
Chloro Fluro Carbons). (If over used could damage ozone), HFC's (Hydro 
Flouro Carbons), Hydrocarbons such as butane and propane, (but flam- 
mable and poisonous), Ammonia (must be handled carefully), Water and 
steam. 

2. Production, use and emission of ozone - depleting chemicals should be 
controlled. 

3. Recycling of these chemicals should be increased. 

4. Servicing of refrigerators and air-conditioners should be regulated. 

5. Refrigirants should be recaptured and used. 

6. Adopt protection measures from sun's radiation. 



Monitoring Ozone depletion 

• In early eighties scientists reported a large hole in the ozone 
layers over Antarctica, where ozone level dropped by 30 percent. CFC 
was the prime suspect for causing ozone depletion. 

• Subsequently a similar hole was discovered over the thickly 
populated northern hemispheres(North Europe and USA). 

• An international agreement made in 1987 at Montreal orga- 
nized by 34 countries (Montreal Protocol) called for reduction in the 
usage of CFC up to 50% by the end of the century. 

• In June 1992 Japanese scientists announced that the ozone 
hole was 1 3 times wider in 1991, than it had been in 1981. 

• In 1990, at London conference the developed countries agreed 
to 100 percent ban of CFCs by 2000 A.D. 

■ In 1991-1992, Scientists working in European Arctic strato- 
sphere Ozone experiment in Sweden sent 39 balloons with payload up to 
500 kg and 800 ozone probes. Their findings revealed that ozone layer 
was reduced by 15-20 percent. Chlorine was also found in active form in 
the atmosphere. 

193 



Waste management 

Human activities related to livelihood and welfare generate waste. 
All wastes are pollutants and they create pollution in one way or other. 
Fundamentally air, land and water pollution results mostly due to improper 
disposal of wastes. 



Pollution, Pollutants 

Pollution is the human caused addition of any material or energy 
(heat) in amounts that cause undesired alterations to water, air or soil. Any 
material that causes the pollution is called a pollutant. 



Classification of wastes 

1. Bio - degradable waste 

These are wastes capable of being removed or degraded by 
biological or microbial action. Waste from agricultural products, animal wastes 
and waste from food processing, leather, fibre, paper and wood etc. come 
under this group. 

2. Non bio-degradable waste 

The substances which are normally not acted upon and decomposed 
by microbes are non-bio degradable wastes. It includes mineral waste, 
mining waste and industrial waste and non-degradable metallic and plastics 
substances. 

3. Mixture of biodegradable and non-biodegraded wastes 

It includes municipal waste and industrial waste. Municipal waste 
contains household garbage, piles of food scrapes, old newspaper, discarded 
and throw away materials, glass, cans, old appliances, broken materials, 
leather shoes, fibres, plastics and others. Construction waste materials, 
packaging materials, sewage, hospital waste, junk and vehicles are varied 
types of urban wastes. All these wastes are found in the form of semisolid, 
solid, semiliquid, sludge and in fly ash form. 

194 



Management of hazardous wastes 

Hazardous wastes may remain dangerous for thousands of years. 
The hazardous waste include radioactive refuse, metallic compounds, 
organic solvents, acid asbestos, organic cyanides, pathological hospital 
wastes, disposable medical equipments and tools. 

The following methods are adopted for the disposal of hazardous 
wastes. 

1. Land fills : There are permanent storage facilities for military related 
liquid and radioactive waste materials in secured lands. High level radio active 
wastes are stored in deep underground storage. 

Wastes are carefully contained to prevent cross - mixing of reactive 
substances. The land fill is capped with impervious clay to prevent infiltration 
and percolation of water through the fill. Fill bottom is lined and provided 
with drainage system to contain and remove any leakage that occurs. 
Monitoring the wells provides a final check. 

2. Deep - well injection : It involves drilling a well into dry, 
porous material below groundwater. Hazardous waste liquids are pumped 
into the well. They are soaked into the porous material and made to remain 
isolated indefinitely. However fractures in the impermeable layer may permit 
the injected wastes to escape and contaminate ground water. 

3. Surface impoundments : This method is used to dispose large 
amounts of water carrying relatively small amounts of chemical wastes. 
Surface impoundments are simple excavated depressions (ponds) into which 
liquid wastes are drained. Solid wastes settle and accumulate while water 
evaporates. If the pond bottom is well sealed and if evaporation equals 
input, wastes may be stored in the impoundment indefinitely. 

4. Incineration : The hazardous biomedical wastes are usually 
disposed off by means of incineration. Human anatomical wastes, discarded 
medicines, toxic drugs, blood, pus, animal wastes, microbiological and 
biotechnological wastes etc are called Bio-medical wastes. 

195 



5. Bioremediation : This is another rapidly developing clean up 
technology. Cleaning the environment with biological options such as 
microbes and plants is called bioremediation. Some naturally occurring 
bacteria and other microorganisms have the capability to degrade or absorb 
or detoxify the wastes such as heavy metals. Many plant materials are 
successfully used as adsorbents for xenobiotics (phytoremediation). 
Genetically Engineered Microorganisms (GEMS) are currently produced in 
large scale to remove the hazardous radionuclides and heavy metals such as 
mercury, chromium, cadmium etc. Certain plants such as Gibberellafusarium 
were able to breakdown cyanide and reduce it to a non-toxic form. The 
bacteria Pseudomonas, nicknamed as 'super - bug' are capable of 
degrading variety of toxic compounds and also degrade oil. 

Management of non-hazardous wastes- Solid Waste Management 

1. Sanitary land fills : The refuse is spread in a hollow land or in a trench 
and compacted with a layer of clear sand fill. The sanitary land fills are far 
more desirable than open dumps but the ground water contamination is 
always a potential problem. Once a land fill operation has been completed 
the site must be inspected periodically. This land fill is suitable for 
recreational activities such as parks and play ground. 

2.Incineration : Municipal incinerators burn combustible solid waste and 
melt certain non-combustible materials. Since the high temperature destroys 
pathogens and their vectors, it is a good method of disposal from health 
point of view. The incineration can reduce the volume of solid waste by 80 to 
90 percent. 

3. Reuse and recycling techniques : Resource recovery is a broad term 
that is used for the retrieval of valuable materials or energy from a waste. 
The separating out of materials such as rubber, glass, paper and scrap metal 
from refuse and reprocessing them for reuse is named as reclamation of waste 
or recycling. 

Paper (54% recovery) can be repulped and reprocessed into 
recycled paper, cardboard, and other paper products; finally ground and 
sold as cellulose insulators or shredded and composted. 

196 



Glass (20% recovery) can be crushed, remelted and made into new 
containers or crushes used as a substitute for gravel or sand in construction 
materials such as concrete and asphalt. 

Some forms of plastics (2.2 % recovery) can be remelted and 
fabricated into carpet fibre, fill for insulated apparel, irrigation drainage, tiles 
and sheet plastics. 

Metals can be melted and refabricated (39% recovery). 

Food wastes and yard wastes (leaves, grass etc.) can be composted 
to produce humus soil conditioner. 

Textiles can be shredded and used to strengthen recycled paper 
products. 

Old tyres can be remelted or shredded and incorporated into 
highway asphalt. 

Waste water treatment and management 

The main steps in typical water - treatment plants are coagulation, 
settling and filtration to remove suspended particles, aeration to remove the 
volatile substances most responsible for taste and odour, and chlorination to 
kill pathogenic organisms. 

For the treatment of sewage, primary treatment consists of 
mechanical filtration, screening, and settling, followed by chlorination. It 
removes 50 to 65% of the suspended solids. 

In secondary treatment the organic wastes are transformed by 
bacteria in the treatment plant, where oxygen is provided by aeration, 
instead of depleting dissolved oxygen in the receiving waters. The sludge 
from this process, consisting largely of bacterial masses, is concentrated and 
processed further in an anaerobic digester. 

197 



Biodiversity conservation (Biosphere reserves) 
Government and non Governmental organizations 

What is biodiversity? 

Biological diversity means the variability among living organisms from 
all sources including terrestrial, marine and other aquatic ecosystems and the 
ecological complexes of which they are parts. It is usually considered at 
three different levels - genetic diversity, species diversity and ecosystem 
diversity 

Reasons for Decline of Biodiversity 

1. Natural causes of Bio diversity extinction 

Studies of the fossil record suggest that more than 99% of all species 
ever existed are now extinct. Most of them were gone before humans came 
on the scene. At the end of Permian period about 250 million years ago, a 
greater disaster wiped 2/3of all marine species and half of all plant and 
animal families. 

2. Human caused reduction 

Natural areas are converted to farms, housing subdivisions, shop- 
ping malls, marinas and industrial centres. For example, when a forest is 
cleared, it is not just the trees that are destroyed, but also every other plants 
and animals that occupy that destroyed ecosystem, either permanently or 
temporarily also suffers. 

Importance Biodiversity conservation? 

Biodiversity is the backbone for agriculture, aquaculture, animal husbandry, 
forestry and a host of other applied branches of biology. Biodiversity is fast 
becoming the fundamental requirement on which the new industrial develop- 
ments and innovations are going to be based. Biodiversity will offer in the 
coming years, new sources of food, medicine and other human requirements. 

To save the races of endangered and endemic species the bio 
resources should be identified and the hotspots in each country should be 
given prior importance to conservation. Only then the remaining species at 
the verge of extinction could be saved. 

198 



Consequences of Losing Biodiversity 

Many species have already become extinct and we do not know 
really what we are losing when we lose species. In future we might lose a 
keystone species, a species whose role is absolutely vital for the survival of 
many other species in an ecosystem. For example, the Orchid bees play a 
vital role in tropical forests by pollinating trees. If they disappear, the 
eventual fall of that ecosystem is evident. This loss may remove and constrict 
the natural habitats in which wild species live. Recreational, aesthetic and 
commercial losses will also be inevitable. 

Conservation of Biodiversity 

The conservation of biodiversity and the growing human population 
are the two great challenges facing our generation and those to follow. The 
following strategies are adapted to conserve biodiversity. 

a. International Conservation Strategies 

Biodiversity should be preserved as the common heritage of all 
humans. All species have a right to exist; one strategy considered as a 
priority is conserving hotspots around the globe. These are areas 
characterized by high concentrations of endemic species and experiencing 
unusually rapid rate of habit modification loss. There are around 25 hotspots 
identified from all over the world. 

b. National Conservation Strategies 

Several measures like legal measures, in situ and ex situ 
conservation efforts, documenting of indigenous knowledge and the 
application of science and technology have been taken by Indian 
government legislations. 

India is one of among the 12 Mega biodiversity countries of the world. 
India was a party to the International Convention on Biological Diversity 
(CBD) in May 1994. The Union Ministry of Environment and Forests is 
co-ordinating an effort to formulate National Biodiversity Action Plan. 

This is being carried out with the help of several other Government and 
Non-governmental organizations, and individuals. 



199 



3. Establishment of Bioreserves 

A biosphere reserve is a unique concept which includes one or more 
protected areas and surrounding lands that are managed to combine both 
conservation and sustainable use of natural resources. 'Biosphere Reserve' 
is an international designation made by the United Nations Educational, 
Scientific and Cultural Organisation (UNESCO). It is based on the basis of 
nominations submitted by countries participating in the Man and the 
Biosphere Program (MAB). The MAB was launched in 1971 to catalyse a 
greater understanding and provision of knowledge and skills to support 
sustainable relationships between people and their environment. Biosphere 
Reserves act as a keystone of MAB by providing a global network of sites 
for cooperative research toward this end. As at the end of November 2002, 
the World Network of Biosphere Reserves included 495 sites in 95 countries. 

Characteristics of a Bioreserve 

• It is a land and/or coastal/marine area in which people are an integral 
component, and which is managed for objectives, ranging from complete 
protection to intensive yet sustainable production. 

• It is a regional centre for monitoring, research, education and training on 
natural and managed ecosystems. 

• It is a place where government decision makers, scientists, managers and 
local people cooperate in developing a model programme for managing land 
and water to meet human needs while conserving natural processes and 
biological resources. 

• Finally, each biosphere reserve is a symbol of voluntary cooperation and 
use resources for the well being of people everywhere. 

Bioreserves in India 

Tamilnadu has the distinction of having a marine biosphere reserve 
viz., the Gulf of Mannar Biosphere Reserve and also a hill Biosphere 
Reserve, the Nilgiri biosphere Reserve. 

200 



Nilgiri Biosphere Reserve: 

The total area is 5,520 sq. km. It is rich in plant diversity. It was 
established to conserve in situ genetic diversity of species and restore 
degraded ecosystem to its natural conditions. 

The Gulf of Mannar Bioshere Reserve: 

This reserve was one of six areas chosen on the basis of its 
threatened status and richness of biological wealth for inclusion into an 
action programme to save India's protected areas for future generations.lt 
encompasses 21 small islands along the coast. It is considered as a 
'biologists paradise' with 3600 species of plants and animals. 

The other biosphere reserves of India are: Nokrek (Megalaya), 
Namdapha - (Arunachal Pradesh), Nanda Devi - (Uttar Pradesh), Great 
Nicobar (Andaman & Nicobar islands), 5. Sundarbans (West Bengal): 



Project Tiger : This programme was launched in 1973. This is started 
with the protection of nine tiger reserves located in different habitats. 
Today there are 23 tiger reserves are under this project to look after tiger 
population and the environment. 



Organizations involved in Biodiversity Conservation 

The organizations involved in biodiversity conservation are 1 .World 
Wildlife Fund: (WWF) 2. Resources for the Future :(RFF) 3. The 
Nature Conservancy: 4. World Resources Institute :(WRI), 5.IUCN 
(International Union for Conservation of Nature and Natural 
Resources), 6. African Wildlife Foundation:(AWF), 7. Genetic 
Resources Action International : (GRAIN), 8. International Science 
Foundation, 9.The Biodiversity Support Program: ( BSP) 

Organizations functioning to preserve and safeguard biodiversity in 
India : 

1 . National Bureau of Plant Genetic Resources in New Delhi. 

2. National Bureau of Animal Genetic Resources at Kamal. 

3. National Bureau of Fish Genetic Resources in Allahabad. 

4. The Union Ministry of Environment and Forests. 

201 



5 . The Foundation for the Revitalisation of Local Health Traditions (FRLHT) 
in Bangalore. 

6. Centre for Ecological Sciences, Bangalore. 

7. World Wide Fund for Nature, India. 

8. Department of Biotechnology, Government of India. 

Energy crisis and its environmental impact 

Energy may be defined as any property, which can be produced from 
or converted into work. In today's world for any development and for all 
industrial operations, energy is a prerequisite. Life is unthinkable without 
energy. Energy production and energy utilization are the indicators of a 
country's progress. Heat, light, electricity are different forms of energy. While 
energy drives the world, the energy generated and utilised affects environment 
on a phenomenal scale. More population, rapid industrialisation, increased 
energy generation, over production, uncontrolled consumption and damages 
to environment are all inter-linked issues. Major issues are slowly being 
converted into crisis threatening our survival. 

Background history of energy usage: 

Fire was probably the first human energy technology. Charcoal from 
fires has been found at sites occupied by our early ancestors. Wind and 
waterpower have been used early as long. Muscle power provided by 
domestic animals has been important for agriculture. The invention of the 
steam engine, together with diminishing supplies of wood in industrializing 
countries caused a switch to coal as our major energy source in the 
nineteenth century. Coal in turn, has been replaced by oil in this century due 
to the ease of shipping, storing and burning liquid fuels. Recently electricity 
and gas (petrol) has changed the economic prosperity and lifestyle in many 
countries. 

Renewable and non-renewable energy sources 

Energy sources that are being made available continuously are known 
as renewable energy sources. (Eg), geothermal energy, wind energy, tidal 
energy, solar energy, ocean currents, nuclear fusion, gobar gas, biomass and 
vegetable refuse etc. 

202 



Non-renewable sources of energy - those sources, which are being 
accumulated in nature from a very long time and cannot be replaced if they 
are exhausted. (Ex). Coal, ores, petroleum, timber, natural gas, electricity 
etc. Fossil fuels like petroleum, natural gas and coal are now providing 
about 95% of all commercial energy in the world. 

Energy crisis 

Energy crisis is due to the increase in population accompanied by 
rapid urbanization and industrialization. Our resources of petroleum and natural 
gas are dwindling day by day. We can hardly expect the oil industry to 
operate at full capacity until the last drop is removed from the ground. It 
appears that we will run out of petroleum and natural gas by about 2020 
unless domestic supplies are extended by taking one or more of the 
following steps. 

Steps to be taken to resolve energy crisis 

1. Reduce the consumption of fuels : The principal target areas are heating 
and transportation, which account for about 1 8% and 25% respectively, of 
our total energy requirements. The consumption of fuel in these areas can be 
reduced by (a)proper insulation of existing buildings and design changes in 
new constructions (eg. using less plate glass), (it saves about 33% of energy) 
(b)improving the fuel economy of automobiles, (c) using more efficient means 
of transportation. 

2. Develop new sources of energy: The energy crisis has prompted the 
development of alternate energy sources (alternatives to fossil fuels) other 
than the heat available from the combustion of fossil fuels. 

(a) Wind Energy : 

In India, the wind power is of great significance as there are large 
coastal, hill and desert areas where wind energy can be usefully exploited for 
generation of electricity and water pumping. 

The harnessing technology of wind energy is simple. The strike of the 
blowing wind on a specially designed blades of a windmill's rotor causes it to 
rotate. This rotation, which is the mechanical energy, when coupled to a 

203 



turbine, drives the power generator. The wind energy thus delivers on the 
spot small quantities of energy. The Indian subcontinent is a high wind zone 
with energy potential estimated at about 20,000 MW. Wind farms are 
already located in Tamil Nadu, Gujarat, and Andhra Pradesh. 

Advantages of wind power : i. Power generation is cheaper. Power is 
procured at 40 paise per unit ii. free from pollution and environmental 
degradation, iii. Since generation is continuous unlike in diesel power, 
investment is never idle. 

(b) Geothermal Energy 

Geothermal energy is fast emerging as a significant source of 
electricity in several island nations, mainly in the Indian oceans and the 
Pacific regions. Geothermal plants make use of naturally heated steam drawn 
to the surface through a series of boreholes. 

Hot Rocks for energy generation 

The Hot Dry Rock (HDR) technology is especially suitable for 
countries like India, where the geological pattern favours easy exploitation 
of this source. Tapping of energy involves drilling of holes several km deep 
into the earth where the temperature of rocks ranges form 200 - 250°C. 
Water is pumped into these bore holes and allowed to circulate through the 
source rock's fracture net work, which may have fissures barely a few 
millimeter wide. This water is then ejected under pressure from a second 
hole in the form of steam. The steam is used to power turbines for electricity 
generation, after which it is condensed back to water that can be used again. 

(c) Mini hydel generation 

Energy generation from small water source is probably the most cheapest 
and reliable of all renewable energy sources. It can be harnessed 
conveniently from nearby canal or stream in a most environmentally benign 
manner. Nature has been very generous and bounteous in providing a vast 
hydro electric potential to the Indian subcontinent. 

(d) Ocean energy 

The various methods of extracting energy from oceans are as follows. 

204 



1. Ocean winds, 2. Ocean waves, 3. Ocean tides, 4. Ocean currents, 5. Ocean 
geothermal, 6. Ocean Thermal Energy Conversion (OTEC), 7. Salinity 
gradient and 8.Bioconversion of sea weeds. 

India's first power plant generating electricity from ocean energy is 
commissioned at Vizhinjam fishing harbour in Kerala to provide energy of 
150 MW in a year. 



Tidal energy : Ocean waves and tides contain large amount of energy. 
Tidal energy is important because it is renewable, pollution free and 
more stable in comparison with hydroelectric power which is depen- 
dent on monsoon cycle. Tidal power plants are being designed in the 
Bay of Canada, Kutch in India etc where tides have been found to be in 
the right range. 



(e) Solar energy: 

Solar energy is another energy source. Each year the earth receives 
from the sun an enormous total of 5 x 10 20 k.cals of energy. Solar energy, 
which is the primary source of all energy forms on the earth, is the renewable 
form of energy. 

Advantages of solar energy: 

(a) Solar energy is a kind of universal, decentralized and non-polluting 
energy (b) it helps considerably in maintaining the ecological balance through 
the process of photosynthesis and green house effect, (c) it has none of the 
disadvantages found in the combustion of fossil fuels such as coal, oil or gas. 

(/) Nuclear energy : 

Nuclear energy is the only energy source, known to be economically 
feasible in the present and for the near future. It can replace fossil fuels. In 
nuclear fission, a heavy atom splits under neutron bombardment into smaller 
fragments, with the evolution of huge amount of energy. In spite of this 
advantage the problem of disposal of nuclear wastes remains. 

Nuclear fusion is expected to be an ideal energy source for the future. In 
nuclear fusion, light nuclei such as deuterium (^H) and tritium (^H) combine 
to form heavier stable nuclei. 



205 



Moreover, the products of fusion are not radioactive and so safety 
hazards associated with fission reactors are greatly reduced. The light 
isotopes needed for fusion are sufficiently common to supply all of our 
energy needs for hundreds of years. Unfortunately, the above fusion reaction 
has not been perfected to sustain flow of energy. 

(g) Bio gas or Gobar gas: 

Gobar gas plants are based on anaerobic fermentation of organic 
wastes in the absence of air. Through gaseous stage the heating efficiency of 
the cattle dung increased production by about 20%. There is a production of 
an organic manure which is about 43% better than dry cattle dung itself. This 
manure can also reduce pressure on naptha-based fertilizers. It has been 
estimated that 10m 3 of biogas has energy equivalent of 6.0 m 3 of natural gas, 
3.6 litres of butane, 7.0 litres of gasoline or 6.1 litres of diesel fuel. 

(h) Hydrogen - Source of power for future 

The hydrogen has been found to be a good choice among all the 
alternative fuel options. It can be produced in virtually unlimited quantities 
with on hand production technologies. It has been established that hydrogen 
can meet all the energy needs of human society, including power generation 
more efficiently and more economically than petro fuels, and with total 
compatibility with the environment. In addition, hydrogen is non-toxic, 
reasonably safe to handle, distribute and use as a fuel. Hydrogen has the 
highest mass energy content - its heat of combustion per unit weight is about 
2.5 times that of hydrocarbon fuel, 4.5 times that of ethanol and 6.0 times 
that of methanol. Its thermodynamic energy conversion efficiency of 30-35% 
is greater than that of gasoline (20-25%). 

Environmental impacts 

1. Thermal Power 

The air, water and soil pollution caused by these plants in terms of fly 
ash, C0 2 , S0 2 , N0 2 and particulates etc. is becoming unacceptable in the 
environmentally conscious society. 



206 



2.Hydel power 

Hydro-electric power generation is associated with displacement and 
resettlement of human population from the site of hydel plant to other places. 
This leads to considerable human problems causing considerable delay in 
the implementation of the project and escalation of its cost. New dams built 
may affect the ecosystem of the locating sites. 

3.Nuclear power 

Radioactive pollutants released form nuclear power plants are chronically 
hazardous. The commissioning of boiling water power reactors (BWRS) have 
resulted in the critical accumulation of large number of long lived 
radionuclides in water. Environmentalists argue that thermal effluents from 
nuclear reactors have acutely affected the aquatic eco system. The 
dangerous radioactive waste cannot be buried in land without the risk of 
polluting soil and under ground water. Several well publicised accidents 
(Ex. Chernobyl disaster at former U.S.S.R.) and radiation episodes have 
given a lot of fear in the mind of general public regarding the radiation 
hazards. 

4. Solar energy 

The use of solar energy, from the environmental viewpoint, is a 
completely safe operation. However, the sites for larger installations of solar 
power plants should be selected without reducing the forest cover. 
Cadmium, used in fabricating thin film solar cells, is both poisonous and a 
possible carcinogen. Carbon dioxide produced while forming silicon from 
silica may increase the atmospheric temperature causing green house effect. 
Silicon dust is also an important occupational hazard. 

5.Fossil fuels 

The burning of coal, oil, wood, dung cakes and petroleum products 
would cause environmental problems. (l)The increase in C0 2 concentration 
is largely responsible for green house effect and global warming, while 
(2) disposal of fly ash requires large ash ponds and may pose a severe problem 
(3)The smoke produced by burning of wood, agricultural by-products or 
animal's dung cake causes respiratory and digestive problems and may also 
lead to eye and lung diseases. (4) Nitrous oxide, Sulphur di-oxide and CO- 
can cause acid rain. 

207 



Poverty and environment 

Poverty is a condition of having insufficient resources or income. It 
is a lack of basic human needs such as adequate and nutritious food, 
clothing, housing, clean water and health services. Extreme poverty can cause 
terrible suffering and death. The world's poorest people - many of whom 
live in developing areas of Africa, Asia, Latin America, Eastern 
Europe - struggle for daily food, shelter and other necessities. They often 
suffer from severe malnutrition, epidemic disease outbreaks, famine and war. 
In wealthier countries - such as United States, Canada, Japan and those in 
Western Europe - the effects of poverty may include poor nutrition, mental 
illness, drug dependence and crime. Extreme poverty, which threatens people's 
health or lives, is known as destitution or absolute poverty. A condition of 
having fewer resources or less income than others within a society or country 
when compared to worldwide averages is known as the relative poverty. 

The cycle of poverty, illness and limited opportunities becomes a self- 
sustaining process that passes from one generation to another. 

Poverty and Environmental issues 

Some favour the argument that poverty leads to environmental 
degradation while others argue that environmental degradation will lead to 
poverty. 

The increase in population and poverty has made an impact on natural 
resources and the environment in many regions. In many parts of the world, 
environmental degradation - the deterioration of the natural environment, 
including the atmosphere, bodies of water, soil and forests - is an important 
cause of poverty. Environmental problems have led to shortages of food, 
clean water, materials for shelter, and other essential resources. As forests, 
land, air and water are degraded; people who depend upon these natural 
resources are adversely affected. As we know, global environmental 
degradation may result from a variety of factors, including overpopulation 
and the resulting over use of land and other resources. Drastic 
environmental degradations may result in poverty. 



208 



Poverty alleviation 

Various measures to eradicate poverty in human society include the 
following: 

a) Achieving self sufficiency by intensifying agriculture, augmenting green 
revolution, increasing crop productivity through modern genetic and bio 
technological approaches. 

b) Increasing land and water resources. Expanding the area of able 
cultivable lands, transforming dry lands into productive lands through 
irrigation water sheds development. 

c) Prevention of land and water pollution by minimizing the usage of 
chemical pesticides and adopting biological control strategies for pest 
eradication. 

d) Establishment of industries and technologies and creating more avenues 
for employment and man power utilization. 

e) Anti- poverty programmes and social security scheme by the 
Governments. 

f) Establishing more primary health centres, hospitals and orphanages for 
destitutes and diseased. 

g) Enforcement of strict family planning methods. 

Fresh water crisis and management 

Clean, fresh water is essential for nearly every human activity. 
Perhaps more than any other environmental factors, the availability of water 
determines the location and activities of humans beings. Almost all 
agricultural operations which supply food to humanity need water. 

Freshwater resources 

Of the total water available on earth, only 3% is fresh water. 

1. Glaciers, ice and snow : Of the 3 percent of all water that is fresh, about 
three - fourths is tied up in glaciers, ice caps and snowfields. They occur 
only at high altitudes or high latitudes. 



209 



2. Ground water : After glaciers, the next largest reservoir of fresh water is 
held in the ground in ground water. Water held in the lower soil layers is 
known as water table. Porous- water bearing layers of sand, gravel and 
rock are called aquifers. 

3. Lakes and Ponds : Lakes are inland depressions that hold standing fresh 
water year around. Ponds are small temporary or permanent bodies of 
shallow water. While lakes contain nearly one hundred times as much water 
as all rivers and streams combined, they are still a minor component of total 
world water supply. 

4. Wet lands : Bogs, swamps, wet meadows and marshes play a vital and 
often a minor role. 

Freshwater shortages 

At least one billion people or nearly 20 percent of the world's 
population, lack safe drinking water. The W.H.O. considers 53,000 gallons 
of good water per year to be the minimum for a healthful life. Some forty 
countries (including island nations, Middle East countries) in the world fall 
below this level. 

Reasons for freshwater shortages 

1. Natural forces 

Deficits are caused by natural forces such as poor rain fall and hot 
winds, rivers changing courses. 

2. Human causes 

Include increased population, rapid urbanization, over grazing by 
cattle, improper cultivation methods, poor sewage systems, inadequate 
finances for providing infra structures. 

3. Depleting ground water 

Ground water is the source of nearly 40 % water for agricultural and 
domestic use in most of the countries. Nearly 95% of rural population 
depends on groundwater for drinking and other domestic purposes. Over 



210 



use of the supplies causes several kinds of problems, including drying of 
wells, natural springs and disappearance of surface water features such as 
wetlands, rivers and lakes. 




Fig. 5.5. Depletion of ground water 

In many parts of the world, groundwater is being withdrawn from 
aquifers faster than natural recharge can replace it. On a local level this causes 
a level of depression in the water table. A heavily pumped well can lower the 
ground water table so that nearby shallower wells go dry. On a broader 
scale, heavy pumping can deplete a whole aquifer. Many aquifers have slow 
recharge rates, so it will take thousands of years to refill them once they 
were emptied. 

4. Salt water intrusion 




Fig. 5.6. Salt water intrusion 

Many parts of the world are losing freshwater sources due to 
saltwater intrusion. Over use of under ground freshwater reservoirs often 
allows salt water to intrude into aquifers and affect the water table. 

211 



5. Loss of free flowing rivers 

Loss of free flowing rivers that are either drowned by reservoir 
impoundments or turned into linear, sterile irrigation channels is yet another 
cause for freshwater crisis. 

6. Evaporations, leakage and siltation 

It happens in freshwater lakes, ponds and dams. 

Freshwater Management 

On a human time scale, the amount of water on the earth is fixed, for 
all practical purposes. There is little we can do to make more water. 
However, there are several ways to increase local supplies. 

a) Seeding clouds 

Seeding clouds with dry ice or potassium iodide particles sometimes 
can initiate rain if water laden clouds and conditions that favour precipitation 
are present. 

b) Desalination 

Desalination of ocean water is a technology that have great potential for 
increasing fresh water. The common methods of desalination are distillation 
(evaporation and recondensation) or reverse osmosis (forcing water under 
pressure through a semipremeable membrane whose tiny pores allow water 
to pass but exclude most salts and minerals). Although desalination is still 
three to four times more expensive than most other sources of freshwater, it 
provides a welcome water supply in such places like Dubai, Oman and Bahrain 
where there is no other access to fresh water. 

c) Dams, Reservoirs, Canals and Aqueducts 

It is common to trap run off with dams and storage reservoirs and transfer 
water from areas of excess to areas of deficit using canals, tunnels and 
underground pipes. 



212 



d) Watershed management 

A series of small dams or tributary streams can hold back water before it 
becomes a great flood. Ponds formed by these dams provide useful wildlife 
habitat and stock- watering facilities. Small dams can be built with simple 
equipment and local labour, eliminating the need for massive construction 
projects and huge dams. 

e) Rain water harvesting 

The activity of collecting rainwater directly or recharging it into ground to 
improve ground water storage in the aquifer is called rain water harvesting. 
By rainwater harvesting the ground water can be conserved, water table 
depletion can be reduced and also sea water intrusion in coastal areas can 
be arrested. To recharge the groundwater rainwater that falls in the terrace 
of the buildings and in the open space around the buildings may be 
harvested. Roof top rain water can be diverted to the existing open / bore 
well. Rainwater available in the open spaces around the building may be 
recharged into the ground by the following simple but effective methods. 




terrace 



house 



rain water percolation pit 



Fig. 5.7. Rain water harvesting 



The Government of Tamilnadu leads the nation in implementing rain 
water harvesting programme. It has made it mandatory for all houses and 
buildings in the State to install rain water harvesting facility. 



213 



f) Better agricultural practices 

Sound farming and foresting practices can reduce runoff. Retaining 
crop residues on fields reduces flooding. Minimizing ploughing and forest 
cutting on steep slopes protects watersheds. Wetlands conservation 
preserves natural water storage capacity and aquifer recharge zones. 

g) Domestic conservation 

We could save as much as half of the water we now use for domestic 
purposes without great sacrifice or serious changes in our lifestyles. The use 
of washing machines, dish washers and low volume shower heads can 
reduce water loss. 

h) Industrial conservation 

Nearly half of all industrial water use is for cooling of electric power 
plants and other industrial facilities. By installing dry cooling systems, this 
could be avoided. Cooling water can be recharged, some industrial 
wastewater may be treated, recycled and reused. 

i) Saving water -an individual's role 

As an individual you can conserve water by the following methods. 

• Take shorter showers. 

• Don't wash car and two wheelers often 

• Don't allow tap run while washing hands, dishes, food or brushing your 
teeth unnecessarily. 

• In your lawn consider planting native plants, a rock garden or some 
xerophytic landscaping. 

• Use water conserving appliances : low - flow showers and low -flush 
toilets. 

• Use recycled water for lawns, house plants and car washing 

• Check taps for leaks 



214 



6. APPLIED BIOLOGY 

Livestock and Management 

The well being of human population is directly linked to the natural 
resources of a country. Natural resources are of various kinds. They are 
plants, animals, land, water and minerals. Animal husbandry and dairying 
have been mainly rural-based, generating employment and revenue among 
the rural people. Extensive studies have been undertaken by ICAR (Indian 
Council for Agricultural Research), State Agricultural Universities, and 
non-governmental research organizations, etc, to improve the livestock and 
its management. Intensive crossbreeding programme in cattle has led to the 
evolution of high-yielding milch animals. 

Dairy 

Dairy operation consists of proper maintenance of cattle, the 
collection of milk, processing the milk, and its by products. Dairying is the 
production and marketing of milk and its products. 

Dairy technology made rapid growth in the later half of the 19 
century. New methods and equipments are available for machine-milking of 
cows. Artificial feeds and nutrient foods are manufactured to improve the 
milk yield of cows. Breeding techniques and applications of biotechnology in 
stock improvement programme of cattle have tremendously increased the 
production of new breeds with high milking capacities. Since milk forms a 
staple food, majority of the Indian population rely on milk for their protein 
supplement. 

Important cattle breeds and their characteristics 

Among mammals, catties belong to the genus Bos (ruminant 
quadrupeds), and the species being divided into Bos indicus (humped cattle), 
Bos taurus (without any hump), Bos bubalis (the buffalo). 

In India at present there are twenty six well defined breeds of cattle 
and six breeds of buffaloes found spread all over the country. Catties are 

215 



classified under three groups based on the purpose they serve to man. They 
are Dairy breeds, Dual purpose breeds and Draught breeds. A breed 

is a group of animals of a species which has for a long period been bred 
among themselves. The members of the breed have closely resembling 
characters and these characters are hereditarily transmissible to young ones. 



Cattle Breeds 

Dairy purpose 

cows are high milk 
yielders, with extended 
lactation. 



1 . Sahiwal 

2. Sindhi 
3.Gir 

4. Umblachery 

5. Karan swiss 



Dual purpose 

cows are meant for 
milk and bullocks 
are meant for 
draught. 

1 . Hariana 

2. Ongole 

3. Tharparker 

4. Kankrej 



Draught purpose 

Bullocks are good 
draught animals 
while the cows are 
poor milk yielders. 

l.Amritmahal 
2. Kangayam 
3.Malvi 
4.SM 
5.Hallikar 



I. Milch breeds (or) Dairy breeds 

The cows of this group are high milk yielders with extended lactation 
periods. The bullocks are of poor draught qualities. These cattle are well 
built with strong limbs, e.g Deoni, Gir, Sindhi and Sahiwal. The cows in do- 
mestic usage for milk are non-descriptive types. 

1. Sindhi (Red Sindhi, Red Karachi) : 




Fig.6.1. Sindhi cow 



Fig.6.2.Sindhi bull 



216 



Origin and distribution : The home of this breed is Karachi and Hyderabad. 

Distinguishing characters : Medium size and compact body. Thick horns 
emerging laterally and ending in blunt points. They have intelligent facial 
expression. Deep dark red colour. Bulls are darker than the cow. They have 
hump and the udder is large with medium sized teats. The animals are 
docile and quiet. Bullocks are steady workers, suited for road and field work. 

Sindhi cows are hardy and have high degree of resistant to heat and 
ticks. These are the most economical milk producers among the dairy breeds 
of India. 

Milk production :- Yields as high as 5,443 kg per lactation period. 

2. Gir (Kathiawarhi, Surti) :- 

Origin and distribution : The breed originated from the Gir forest of South 
Kathiawar. Impure forms of Gir breeds are found in Baroda and some parts 
of Maharastra. 

Distinguishing characters : The colour is not always entire. Most of these 
cows have spotted skin. It is usually red, black and red, red and white or 
white with red spots. The body is well built with clear cut lines. The pure 
breed has a majestic appearance. Ears are long like a leaf. Tail is long and 
whip like. Legs are long and well built. Udder is large with matching teats. 
Bullocks are heavy, powerful and good for draught. 

Milk Production : Gir cows are good milk yielders. In some, the maximum 
yield is 3,715 Kg per lactation period. 

II. Dual purpose breeds : This breed of cattle are meant for both milk 
yield and draught works. The cows are fairly good milkers and the bullocks 
are sturdy and are useful in draught works like ploughing the field, transport, 
cart pulling etc. Important examples are Hariana and Ongole. 

1. Ongole : Nellore 

Origin and distribution :- Ongole tract of Andra Pradesh, Guntur, 
Narasaraopet, Venukonda, Kandukur taluks of Nellore. 

217 




Distinguishing characteristics : This breed is a larger form. The matured 
male weighs about 700Kg and female weighs about 400 Kg. Ongole breed 
is usually white in colour with grey marking. Males are dark grey at 
extremities. Hump is well developed and erect. The horns are stumpy and 
they grow outwards and inwards. Bullocks are powerful and suitable for 
cart and road work but are not fast. 

Productions : Cows are good yielders, yielding from 1700 kg to 3500kg 
per lactation. 

III. Draught breeds : These breeds are exclusively meant for pulling 
carts, ploughing fields etc. They are well-built and the skin is well stretched. 
The bulls are used for draught works. The cows are poor milkers. Important 
Indian draught breeds are Amrithamahal, Kangayam, Malvi, Hallikar etc. 



1. Kangayam (Kanganad, Kongu) :■ 




218 



Origin and distribution : It originated from Kangayam divisions of 
Dharapuram taluk of Coimbatore district in Tamilnadu. The breed is also 
found in Udumalapet, Palladam, Pollachi and in other parts of South India. 

Distinguishing characters : The cattle of this breed are of moderate size 
and the colour of the body is white or grey with black markings. The horns 
are strong and are curved upwards and outwards. The head is short with 
prominent forehead. Neck is shorter and thick and the ears are smaller and 
pointed. They have moderate sized hump, wide muzzle, strong limbs, fine 
skin and a fine tail. The udder is medium sized with small teats. The bulls are 
excellent type for hard work. 

Production : The cows are poor milkers, yielding about 666 kg per lactation. 

2. Hallikar 

Origin and distribution : Commonly found in the South Indian States, 
predominantly in Karnataka. Hassan and Tumkur regions of Karnataka are 
the home places of this breed. 

Distinguising characters : Body is dark grey in colour, some times almost 
black. The animals are of medium size. The head is usually long with a 
bulging forehead and a prominent furrow in the middle. The face is long with 
small ears. The long horns emerge out, slant backwards in a graceful sweep 
and then curve upwards to terminate in a sharp point. The hump is 
moderately developed. The udder is medium sized with small teats. The 
Hallikar bullocks are draught breeds. They are used for heavy ploughing, 
transport and other field works. 

Production : The cows are poor milkers. 

Exotic breeds of cattle : Many milk yeilding breeds of cattle are 
imported and reared in India. The exotic breeds are successfully crossed 
with indigenous breeds to obtain cross breeds, which have sufficient 
desirable characters. European breeds are the first kind of exotic breeds 
introduced in India about 90 years back. Important ones are short horns 
Ayreshire, Jersey, Brown swiss, Holstein Friesean, Guernsy and Red Dane. 

Jersey : Jersey is one of the oldest dairy breed. It originated from Jersey 
island adaptable to wide range of climatic conditions and heat. The colour 

219 



of the breed ranges from white to dark grey, and it is broken and found as 
patches. Jerseys are nervous and sensitive animals. Jerseys have good ud- 
ders with large teats. The lactational yield is 4,950 kg with milk fat 5% . The 
milk has a characteristic yellow colour because of high carotene content. 
The bulls are vicious than other breed. Cross breeding of Jersey and indig- 
enous Sindhi and Hariyana produced excellent cross breeds with more than 
2000 kg of milk yield per lactation period. 




Common diseases and control : Cattle are subjected to a large 
number of diseases. Cattle in normal health appear bright, alert and active in 
their movements with a shiny coat. They also enjoy normal appetite and sleep. 
Cattle in ill health appear dull, restless and change posture frequently with a 
drop in milk yield. 

Contagious diseases : The diseases which spread easily by various modes 
are called contagious diseases. These diseases are of bacterial or viral origin. 
The bacterial diseases are anthrax, haemorrhagic septicemia, mastitis 
and tuberculosis. The viral dieases are cow pox, foot and mouth disease 
and rinderpest. 

1. Anthrax : Anthrax, a bacterial disease is due to |3 anthracis which causes 
sudden death in cattle. 

Symptoms : High temperature (41-41. 5°c), swelling of the neck, thorax, 
flanks and lumbar regions which are neither hot nor painful. Blood discharges 
from natural openings, the affected animal dies in 10 to 36 hrs. 

Control : Vaccination with spore vaccine at the age of 6 month and then 
annually. Affected animals are to be segregated, contaminated place to be 
disinfected and the carcasses to be burried deep. 

220 



2. Cow pox is a contagious viral disease attacking cows and buffaloes. 

Symptoms : Retarded rumination, swelling of udder and teats, rise in 
temperature, eruptions on skin and udder and teats developing into vesicles, 
pustules and scabs by stages ultimately leading to mastitis and loss of milk. 

Prevention : Segregation of affected animal, giving sloppy food for 
swallowing and digestion, fomenting udder with warm disinfectant solution, 
giving saline laxative and diuretics, treating lesions with mild antiseptic 
ointment. Cow shed should be kept clean. 

3. External parasitic diseases : Common ectoparasites are flies, ticks, 
mites, fleas and lice. They are directly involved by sucking the blood from 
cattle and become an irritant. They are also indirectly involved in transmitting 
bacterial, viral and protozoan diseases. 

4. Internal parasitic diseases : Hook worm, round worm, tape worm and 
flukes are some of the intestinal parasites causing diarrahoea, dysentry and 
some other complications. 

Non-contagious diseases : The diseases which does not spread by 
external modes but are caused by physiological or genetical means is known 
as non contagious diseases. 

1. Milk fever : Milk fever is common in high milk producing cows and 
buffaloes during the early part of the lactation. It is due to inability of the 
animal to assimilate calcium from the feed, leading to demineralization in the 
bone. The serum Ca and P levels become low and the sugar level gets 
increased. 

Symptoms : Staggering, loss of appetite, temperature becoming below 
normal, pulse rate becoming high, restlessness and become inactive. 

Precaution and first aid : Feeding jaggery along with lime water, few days 
prior to calving and giving soft nutritious and easily digestible food for a few 
days after calving prevents milk fever. Cleaning the udder with warm cloth 
and preventing infection from the floor. Pumping clean air into the udder and 
massaging are other measures to be adopted. 

2. Constipation : Constipation is severe due to over eating of coarse 

221 



fibrous roughages, inadequate intake of water and lack of exercise. Which 
leads to lack of appetite, lack of rumination or chewing and dull 
appearance. 

Precaution and first aid : The affected animals can be given wheat bran 
meal or rice gruel and succulent fodder. Plenty of drinking water with jaggery 
or salt, evacuating the rectum by giving warm soap water enema and 
massaging the abdomen are the other measures of treatment. 

Techniques adopted in cattle breeding 

A. Out breeding : Out breeding is mating of less closely related or unre- 
lated animals. The individuals involved do not have a common ancestor in the 
preceeding 4-6 generations. 

B. Cross breeding : Cross breeding is mating of animals of different breeds. 
It is valuable as a means of introducing desirable characters into new breed 
in which they have not existed formerly. The cross breeds exhibit increased 
growth and vigour by the blend of desirable dominant genes from two breeds 
in the first generation. 

C. Artificial insemination : Artificial insemination is the deposition of male 
reproductive cells (spermatozoa) in the female reproductive tract by 
mechanical means rather than by natural mating. The semen is collected from 
the male by artificial means. The semen is inseminated into the female by 
placing a portion of it either in a collected or in a diluted form into the cervix 
of the uterus by mechanical methods at the proper time and under most 
hygienic condition. 

It helps to eliminate the need for maintenance of herd sire, permits long 
distance transport of semen by air, avoids spreading of genital diseases, 
and increase the rate of conception. Further this method helps better 
recording, permits use of semen from injured and old bulls and provides a 
chance of detecting any genital abnormalities or pathological infection and 
inflammation in cows. 

Poultry 

The term poultry refers to the rearing and breeding of avian species 
such as chickens, ducks, turkeys, geese and guinea-fowls which have been 

222 



domesticated. They are the best converters of feed into animal protein 
compared to other livestock. Chickens are the most common poultry 
enterprises. Chickens alone occupy 90% of the total poultry. 

Breeds 

There are more than hundred breeds and more varieties of fowls. 
The fowls are classified based on their utility to man. They are meat type, 
egg type, dual type and games and ornamental type. Based on their origin 
there are four major exotic breeds of fowls. They are American breeds, 
Asiatic breeds, English breeds and Mediterranean breeds. In addition to the 
above many of the indigenous breeds are also reared. 

/. American breeds:- 

Most of the American breed of fowls are dual purpose forms giving 
meat and egg. These breeds are characterized by yellow feathers, red ear 
lobes and many of them lay brown-shelled eggs. Rhode island reds, 
Plymouth rock, New hampshire and Wyandotte are some of the 
important breeds of American class. 

a. Plymouth rock:- Plymouth rock is the oldest and most popular breed of 
America. The birds are single combed with long and deep body . The breed 
produces good sized eggs. The plumage is generally greyish white. 
The female looks darker in colour than males. This colour feature is used to 
distinguish the sex of the birds. The females usually have black spots on the 
shanks. 




Fig.6.2.1. Plymouth Rock Hen Fig.6.2.2. Plymouth Rock Cock 




b. White plymouth: The white plymouth rock has white plumage throughout 
the body and it is commonly used in broiler production. Standard weights of 
cock, 4.3kg; hen 3.4kg; cockerel, 3. 6kg; pullet, 2.7kg. 

223 



//. Asiatic breeds:- 

The breeds of this class belong to Asian continent. They are 
characterised by large body with heavy bones, feathered shanks, red ear 
lobes and yellow skin. They are used for egg and meat purpose. The egg 
shells are light to dark brown in colour. The important breeds of this class 
are Brahma, from Brahmaputra valley in India, Cochin and Langshan are 
from China. 

Brahma :- Brahma breed is well known for its massive body with heavy 
bones, well - feathered and proportionate body. Peacomb is one of 
important breed character. Light, Dark Brahma are of two common varieties 
of Brahma . 





Fig.6.2.3. Brahma Hen Fig.6.2.4. Brahma Cock 



Light Brahma :- It has light grey to white colour and the hackle feathers 
are black. The beak and legs are light yellow coloured. Standard weights of 
light Brahma are, cock 5.4 kg; hen 4.3 kg; cockerel 4.5kg; and pullet 3.6 kg . 

Dark Brahma:- Dark brahmas are light black or steel grey coloured with 
greenish hackle, standard weight of dark Brahma are, cock 4.9 kg; hen 
3.9 kg; cockerel 4.0 kg; andpulet 3.1 kg. 

///. English breeds :- 

All the breeds of this class originated from England. Presence of white 
plumage and pink coloured earlobes are the characters of the breed of this 
class. Most of them lay brown shelled eggs. Sussex, Orpington, Australorp 
and Corinsh are some of the important breed of this class. 

IV. Mediterranean breeds:- 

Breeds of this class originated from European countries which are by 

224 



the side of Mediterranean sea. The important breeds of this class, Leghorn 
and Ancone originated from Italy whereas Minorca originated from spain. 
The breeds are light bodied with non feathered shanks. The fowls of this 
class lay white shelled eggs and they are non-sitters. 

Leghorn:- The white leghorns are the most popular and commercial breed 
in India, Colours of plumage may be white, brown or black. The fowls of 
this breed are small, compact with single comb and wattles. Though the 
leghorns are adapted to most of the climates, they are thriving well in dry 
areas. They mature early and they begin to lay eggs at the age of 5or 6 
months. Hence, the breed is economically important and preferred in 
commercial forms. The standard weight of the cock is 2.7kg; hen 2.0kg; 
cockerel 2.3kg; and pullets 1.8kg. 





Fig.6.2.5. Leghorn Hen 



Fig.6.2.6. Leghorn Cock 



V. Indigenous breeds of fowls: 

The common country hen of India is known as 'Desi' which is the 
best mother for hatching. Some of the Indian fowls resemble the leghorn, but 
have poor laying qualities. Chitagong, Aseel, Karaknath and Busra are four 
breeds of indigenous fowl in India. 

a. Aseel:- Aseel is noted for its pugnacity. The colour of the breed is white 
or black. The hens are not good egg layers but are excellent sitters. Aseel 
breed is found in almost all states of India, but abundant in Andhra Pradesh. 

b. Chittagong:- Chittagong breed is largely found in West Bengal. The 
plumage colour varies, but the popular shade is golden or light yellow. The 
beak is long and yellow in colour, the ear lobes and wattles are small and red 
in colour. They are good egg layers and are delicious. 

225 



c. Karaknath:- It is a fowl with black flesh. It is abundant in Madhya Pradesh 
and bred by tribals and the eggs are light brown in colour. The adult plumage 
varies from silver and gold-sprangled to bluish- black. The comb, wattles 
and tongue are purple in colour, 

d. Busra:- This is a small to medium sized bird found in some parts of Gujarat 
and Maharashtra. They are light feathered with wide variation in body colour. 

Farming methods 

Poultry farming has now become very popular. It is recoginzed as an 
organised and scientifically based industry with tremendous employment 
potential. It plays an important part in the rural economy of India. It provides 
a ready source of income to the cultivator. Besides meat and eggs, poultry 
supplies feathers and rich manure. The following factors are being taken into 
consideration for the growth of poultry farming 1) small initial investment 
2) availability of quality chicks 3) short generation interval 4) quick, assured 
and better returns compared to other livestock species 5) availability of 
trained man power 6) better understanding and knowledge of the improved 
and scientific methods of feeding 7) management and health control. 

Rearing involves the following stages:- Selection of eggs, incubation and 
hatching of eggs, brooding or care of new borns, housing of poultry, feeding 
of poultry are the important steps in rearing of chickens. 

1. Selection of eggs:- Eggs meant for hatching and rearing must be selected 
very carefully. The following points should be considered during selection of 
eggs. 

(l)The egg should be fertile (2) Over-sized and small sized eggs should 
not be selected instead medium sized should be preferred (3) Dark-brown 
shelled eggs hatch earlier than light-brown shelled eggs (4) Freshly laid eggs 
are preferred for rearing. 

2. Incubation and hatching: 

The fertilized hen's egg undergoes development during incubation and 
hatching processes. The fully formed bird emerges out of egg after a hatching 
period of 21-22 days. During this period the egg must obtain optimum 

226 



temperature, humidity and ventilation etc. The maintanance of newly laid eggs 
in optimum condition till hatching is called incubation. 

The incubation is of two types namely natural incubation and 
artificial incubation. In the natural incubation method, the eggs are 
subjected to the care of mother. Only a limited number of eggs can be 
incubated by a mother hen. In artificial incubation the eggs are maintained in 
a chamber(incubator) which stimulates the optimum environmental 
condition. In artificial incubation more number of eggs can be incubated than 
natural incubation. 

3. Brooding :- Brooding is the care and management of young chickens for 
four to six weeks immediately after hatching. Like incubation, brooding also 
has the natural and artificial methods. In the former, day-old chickens are left 
to the care of mother and in the latter temperature controlled artificial brooder 
is used. 

Factors involved in brooding : 

Temperature :- The hatched chicks are kept inside the incubator for about 
36 hours and then transfered to artificial brooder. The optimum temperature 
is 33°c during the first 3 days. During the subsequent weeks of brooding the 
temperature is reduced by 3°c each week till it reaches 21°c. 

Ventilation :- Fresh air movement is important for good health and proper 
growth of the chicks. Poor ventilation results in the accumulation of carbon 
monoxide, ammonia and water vapour which may lead to microbial 
infection. 

Floor space :- Adequate floor space is to be provided for the proper 
development of chicken. Minimum 500sq.cm of floor space per chickens is 
to be provided. Crowding of chickens leads to poor growth and induces 
cannibalistic tendencies amongst the birds. 

Litter :- The floor of the brood house is layered by beds of hay, rice husk or 
saw dust and this is called litter. The litter bed should be 5 to 7.5cm thick 
and it must be kept dry. 

Light :- To keep the brood house free from infectious germs, the brood 
house must be well ventilated. Evenly distributed sunlight promotes proper 
growth of the birds and formation of vitamin D. 

227 



4. Housing of poultry :- Open sided poultry is popular in our country. The 
primary objective of providing housing to poultry is to protect them from 
sun, rain and predators and to provide comfort. Poultry house should be 
well ventilated. It should be kept cool in summer and warm in winter. The 
floor of the poultry house should be moisture-proof, rat proof, free from 
cracks, easily cleanable and durable. 

Poultry feeding :- Feeding of poultry bird is an important part of rearing. 
The diet of chickens must contain adequate amount of water, carbohydrates, 
proteins, fats, vitamins and minerals. The food stuffs such as maize, barley, 
sorghums, wheat, oil cake, rice etc are to be given in standard requirements. 

Poultry byproducts 

Poultry and poultry products are highly perishable. Hence, due 
attention has to be paid to the problems relating to processing, preservation 
and marketing of poultry and poultry products for the benefit of producers, 
processors and consumers. In a poultry processing unit, raw materials go as 
waste in the form of blood, feathers, heads and feet. Hatchery waste 
includes infertile eggs, dead embryos, and hatchery unstable chicken. Large 
quantity of wet droppings are also available. Processing and using of this 
byproducts will not only reduce the cost of poultry production, but also solve 
the disposal problem and minimize pollution hazard. A great deal of work 
has been done for processing this by-products into feather-meal, poultry 
byproducts meal, hatchery byproducts meal, egg shell meal, albumin flake, 
dried and poultry manure. 

Poultry diseases : These birds are commonly affected by diseases such as 
ranikhet, coccidiosis, fowl pox and tick fever. 

Pisciculture 

Pisciculture or fish culture, included under the broad term 
'aquaculture', can be defined as the 'farming and husbandry of economically 
important fish, under controlled conditions' . 

Fish farming is a productive venture. Fishes are highly nutritious 
sources of easily digestible proteins (rich in lysine and methionine. They are 
essential amino acids); minerals like calcium, phosphorous, iron, sodium, 
potassium, magnesium and sulphur; vitamins such as A, D and health 
promoting fats. Fish are the source of polyunsaturated fatty acids which are 

228 



helpful in cholesterol regulation and promoting cardiac health. Fish farming 
can help in integrated rural development by generating employment 
opportunities. 

Fish farming 

Definition 

Fish farming is the raising of fish for personal income or profit. Based 
on the environment in which culture is done, fish farming may be categorized 
as freshwater fish farming, brackish water fish farming, saltwater or marine 
fish farming (mariculture). 

Characters of cultivable fish 

The following criteria should be considered before selecting a fish for 
farming purpose. 

■ Rate of growth :Fish which grow to a larger size in shorter period are 
suitable for culture.Eg. Carps. 

• Adaptation to climate: The cultured species of fish should be able to 
adapt to the local climatic conditions of the farm. 

• Tolerance: The fish should have the capacity to tolerate wide fluctuations 
in the physico chemical conditions such as oxygen, salinity, temperature etc 
of the water. 

• Acceptance of artificial feed : When more number of fish is to be accom- 
modated in a limited space, there is the need for supplementary feeding on 
compounded diets. The fish should show ready preference for these feeds. 

■ Resistance^ is desirable that the cultured fish is hardy enough to resist the 
common diseases and attack of parasites. 

• Amiability and compatibility: The fishes proposed to be cultured 
together ('poly culture') should be able to live together without interfering or 
attacking the other. 

■ Conversion efficiency: The species offish which give more edible flesh 
per unit of food consumed, is preferred. 

229 



■ Consumer's preference: Food preference of people vary with the 
geographic regions. Hence, the species cultured should be easily marketable 
locally or to the targeted consumers. 

Culturable Fishes of India 

Carps, Catfishes, Murrels, Tilapia etc are the main culturable fishes. 



Culturable Fishes of India 
Indian major carps 

Carps (Kendai) 

Catla catla (Catla) 
Labeo rohita (Rohu) 
Cirrhina mrigala (Mrigal) 

Exotic (Chinese) carps 

Cyprinus carpio (Common carp) 

Minor Carps 

Labeo bata (Bata) 

Catfishes ('Keluthi') 

Wallago attu (freshwater shark : 'Valai') 

Mystus aor (Cat fish) 

Clarias batrachus (Magur) 

Murrels or snake heads ('Viral') 

Channa striatus (Striped snake - head) 

Tilapia 

Oreochromis mossambicus ('Jilebikkendai') 

Sport fishes (Cold - water fishes) 

(i) Trouts (Order : Salmoniformes) 
Salmo gairdneri (Rainbow trout) 



230 




„>f\f: i«#* 



Black pamfret 




■■■-•: f- 







Indian mackerel 



% 



* 



Indian oil sardine 





Catfish 



231 



Marine fishes 

Lates calcarifer (Sea bass or cockup, 'Koduva') 

Mugil cephalus (Grey mullet, 'Madavai') 

Chanos chanos (Milk fish) besides these food fishes, there is an enormous 

potential for the mass culture of a variety of ornamental fishes, which can 

bring in high profit, also from overseas markets. 

Fish Pond 

A successful aquaculture practice with a good harvesting is usually 
due to proper construction preparation and maintenance of the fish pond. 

Types of fish ponds 

Within the fish farming pond system there can be different pond com- 
ponents, namely nursery, rearing, production, segregation and breeding or 
spawning ponds. The area percentage of these ponds in a fish-farming 
complex can be: 

Nursery pond - 3% 

Rearing pond - 11% 

Production pond - 60% 

Segregation pond - 1% 

Breeding pond - 25% 

Nursery ponds are shallow, while the others are moderately deep. In 
larger production ponds, water can be maintained at a depth of 2 and 3 
metres. A fencing around the fish farm, may be constructed for protection. 

Preparation of pond 

Before the culturing offish, the pond should be conditioned. 

Conditioning 

A layer of lime (calcium hydroxide) is spread over the bottom, for 
two weeks. It removes the acidity of the soil, facilitates desirable 
geochemical cycles and kills unwanted soil organisms. 

Water may be let in slowly after two weeks and filled to the desired 
depth. The quality parameters such as temperature, oxygen content, pH, 

232 



turbidity, hardness, alkalinity and plankton growth should be checked for 
their optimal levels, before stocking the fish. 

Manuring 

After 15 days of liming, the fertilization is to be done in order to 
develop the fish food organisms (phytoplankton and the zooplankton: macro 
and micro). Manure may be of organic or chemical nature. Organic manure 
may be urine or sewage rich in nitrogenous matter,cow dung, pig dung, 
poultry manure and plant manure such as green manure, compost, oil cake 
etc. If the organic carbon is less, cow dung for the stocking pond is applied 
at the rate of 2-3 tonnes / ha. Poultry manure at the rate of 5000 kg / ha is 
known to enhance zooplankton induction. Use of chemical fertilizers should 
vary according to the concentration of phosphorus and nitrogen in the soil. 
The standard combination of NPK as 18 : 10 : 4 is generally 
recommended for freshwater ponds. For a production pond of medium 
fertile soil; urea at the rate of 200 kg / ha / yr or ammonium sulphate at the 
rate of 450 kg / ha / yr may be applied in split up dozes, alternating with 
organic manure. 

Management of fish farm 

Feed and water quality are the two major factors governing the 
productivity of the fish culture pond. Besides, seed quality, stocking and other 
management measures also determine the extent offish production. 

Water quality involves the regulation of 

Temperature at 25-33°C, dissolved oxygen, pH (6.5 - 9.0 ), 
hardness, alkalinity, turbidity and plankton culture etc.. 

Feeding 

Apart form natural food, most cultured species take artificial feeds. 
In general artificial feed should contain 30-40% protein, 5-10% fat, 
50-60% carbohydrate, less than 5% cellulose, 10% water, vitamins and 
minerals. Animal and vegetable ingredients can be used in formulating feed 
pellets. Fishmeal, prawn meal, soybean meal, silkworm pupa, wheat, 
tapioca, slaughter house wastes, rice bran, aquatic weeds, oilcakes etc are 

233 



good feed ingredients. Usually Indian farmers give rice bran and oil cakes in 
powder form to major carps. Carnivorous fishes such as murrels and 
catfishes may be provided with trash fishes. For adult fish, daily 
supplementary feeding can be at 2% of its body weight. 

Routine Management and Diseases 

Analysing water parameters, replenishment of water, aeration, 
regular feeding, observation for mortality and disease symptoms should be 
routine checks in the management of aquaculture ponds. Diseases can be of 
viral or bacterial origin or may be due to ectoparasites or endoparasites. 

Edible Fishes Of Tamilnadu 

1. Fresh Water Fishes 

Among the freshwater fishes, carps belonging to the order 
Cypriniformes form significant components of reservoir, riverine and culture 
fisheries. They have no teeth in any part of their mouths, however 
pharyngeal teeth may be present. 

1. Indian Major Carps ('Kendai' meen) 

a) Catla catla (catla) : Catla has a deep body with prominent head, large 
upturned mouth, non-fringed lips, devoid of barbels and a broad dorsal fin 
with 14-16 branched rays are the identifying features. It feeds on 
zooplankton of the pond surface using large gill rakers; however, young ones 
(15-20 mm) feed on zooplankton and phytoplankton. It grows to a 




Fig. 6.3.3. Catla catla 

234 



maximum size of 1 .8 m (45 kg). It is a fast growing species among the Indian 
major carps. First year growth is 35-45 cm and about 1.5 - 2.0 kg. It 
matures in the second year. 

b) Labeo rohita (Rohu) : Of all the carps, this is considered as the tastiest 
fish. It has a small and pointed head, terminal small mouth with fringed lower 
lip. A dorsal fin with 12-13 branched rays and full reddish scales are its 
identifying features. It is a column feeder on phytoplankton, plant debris or 
decaying debris of aquatic plants; however, the young ones feed on zoop- 
lankton. The maximum size attained is lm. It is fairly fast growing species 
and first year growth is 35 - 40 cm and 900 g. 




Fig. 6.3.4. Labeo rohita 

c. Cirrhina mrigala (Mrigal) : A linear body small head with blunt snout, 
subterminal mouth with thin non-fringed lips, dorsal fin with 12-13 branched 
rays and a bright silvery body having golden tinge are its identifying features. 




Fig. 6.3.5. Cirrhina mrigala 

235 



It is a bottom feeder on decaying organic and vegetable debris; however, its 
young feed on zooplankton. The maximum size attained is 0.9 m. Its growth 
in the first year is about 30 cm (700 g). 

(iv) Catfishes (Order: Siluriformes-'Keluthi') 

The catfish are air-breathing, or live-fishes as they are capable of 
directly breathing atmospheric air. They can live for a long time without 
water and can therefore be transported live and in fresh condition over long 
distances. The body is without scales and each of the upper and lower jaws 
possesses two pairs of long barbels in each. The mouth is non-protractile 
having jaws with teeth. Majority of the catfish are predatory and 
cannibalistic, feeding on all pond animals including fish fry. 

v. Murrels or Snakeheads (Order : Channiformes-'Viral' meen) 

These fish are also air-breathing and have a good demand. 
Elongated and cylindrical body, depressed head, large and protractile mouth 
are its identifying features. Murrels are suitable for culture in irrigation wells 
and shallow swamps. 

a) Channa marulius (Giant snakehead) : Dorsal and anal fins of this species 
are long and without spines. It reaches a maximum size of 1 .2 m. It is suitable 
for culture in ponds along with tilapia, the young ones of which serve as food 
source to this species. 

b) C.striatus (Striped snake-head or Common murrel) : Stripes are present 
on its body. Attains a maximum size of 90cm. 

vi. Tilapia (Order : Perciformes) 

a) Oreochromis mossambicus (Tilapia -'Jilabi' kendai) : An exotic fish 
introduced in India from East Coast of Africa in 1 952. It is characterized by 
an anterior spinous dorsal fin and posterior soft dorsal fin. Maturity occurs 
even in two months old individuals. It breeds nearly eight times in a year. 
Female keeps the fertilized eggs guarded in its mouth. 

II. Brackish water Fishes 

Brackish water fishes spend most of its life in river mouths 
(estuaries) back waters, mangrove swamps and coastal lagoons. These are 

236 



Chanos Chanos (Milk fish), Grey mullets ('Madavai'), Pearl spots 
('Kari'meen), Seabass ('Koduva'), The Seabreams. 

III. Marine Fishes 

Marine edible fishes of Tamilnadu coast include both cartilaginous 
and bony fishes. 

Elasmobranchiata 

Cartilagenous fishes are the sharks and skates. 

Bony Fishes are 

i) Pomfrets ('Vavva'): ii) Indian Mackeral ('Kanangeluthi') : iii) Seer fish 
('Vanjiram' or 'Neimeen'): iv) Carangids ('Para' meen):(v) Ribbon fishes: 
(vi) Catfishes ('Keluthi'): (vii) Flat fishes ('Naakku meen'):(viii) Sardines 
('Maththimeen'). 

Medical Lab Techniques 

In medical therapeutics both diagnosis and treatment are the two 
important vital aspects. Diagnosis involves identifying or determining the 
nature of disease while treatment involves the curative aspects in order to 
eliminate the disease causing agent. The clinical laboratory tests help a 
physician in correct diagnosis and treatment. 

1. Stethoscope: 

A stethoscope is used to hear the heart beat sounds, sound due to 
inhalation and exhalation of air in the lungs and the respiratory pathways and 




Fig. 6.4.1. Stethoscope 

237 



also the stomach movement. It is a very useful diagnostic tool to help localize 
problems and to diagnose disease. Stethoscopes are also used along with 
the sphygmomanometer. The first usable binaural stethoscope was invented 
in 1855. The modern electronic stethoscopes are high precisioned 
instruments. These can be used to hear a patient's heart and lung clearly 
even in high noisy environments and even through layers of clothing. The 
electronic stethoscopes also make it possible to hear the foetal sounds in 
mother's womb. 

Uses: 

1. Stethoscope helps to find normal (lub-dub) versus abnormal heart sounds 
(heart murmurs) and also to diagnose valve functions. 

2. Stethoscopes can indicate fluid in lungs in case of pneumonia and 
pulmonary edema. It can diagnose airway diseases like bronchitis and 
pleuritis. 

3. Stethoscopes are also used to compare the movements in the normal 
versus overactive or underactive intestinal tract. 

2. Sphygmomanometer: 

A sphygmomanometer is an instrument used to measure blood 
pressure. The word is derived from the Greek sphygmus (pulse) plus the 
scientific (physical) term manometer. 

Arterial blood pressure is the force of pressure, which the blood is 
exerting on the walls of the blood vessels in which it flows. The blood 
pressure in the artery varies during the cardiac cycle. The cardiac cycle is 
defined as the cycle of events that take place during one systole and diastole 
of the heart. Systole refers to contraction and diastole the relaxation. During 
ventricular systole, when the left ventricle is forcing blood into the aorta the 
pressure rises to a peak which is referred to as systolic pressure. During 
diastole the pressure falls and the lowest value reached is referred to as 
diastolic pressure. 

The blood pressure depends partly on the force and volume of blood 
pumped by the heart and partly on the contraction of the muscles in the walls 

238 




scale 
manometer 

nozel 
rubber tube 



rubber bag with 
linen cuff 



-^uLiiiliillii 



~metalic hook 
^adjusting screw 
s rubber pump 

Fig. 6.4.2. Sphygmomanometer 




Fig. 6.4.3. Method of measuring blood pressure 



of the arterioles. Blood pressure changes during physical exercise, during 
anxiety and emotion and in sleep etc. However a prolonged or constant 
elevation of blood pressure, a condition known as hypertension can increase 
a person's risk for heart attack, stroke, heart and kidney failure and other 
health problems. It is always suitable to measure blood pressure when a 
person is in a relaxed and in resting condition. 

The normal blood pressure value is 120/80 mm Hg, in which '120' 
denotes the systolic pressure and 80 the diastolic pressure. 

There are two types of sphygmomanometer viz., Monometric type 
and 2. Digital (modern) type. 

Uses: 

1. Sphygmomanometer helps to estimate the state of blood circulation and 
the working of heart. 

2. Sphygmomanometer helps to diagnose pathological conditions such as 
hypertension (increased BP) and hypotension (reduction in BP). 

Haemocytometer 

The counting of blood cells after proper dilution is known as 
haemocytometry and the instrument used to count the blood cells is called 
haemocytometer. Using haemocytometry method, red cells, platelets and 

239 



eosinophils are often counted. Now-a-days it is also used for counting cells 
of bacteria, yeast, or algae. 

Haemocytometer - instruments description 

A haemocytometer consists of a counting chamber, a coverglass for 
the counting chamber and diluting pipettes. Many types of counting 
chambers are available. Improved Neubauer and Fauchs Rosenthal are the 
two most commonly used counting chambers in laboratories. 

RBCs and WBCs in blood cannot be counted as such. The blood 
has to be diluted in specific isotonic solutions. RBC, diluting fluid is called 
Hayem's solution. ForWBC counting Turk's solution or Tois son solution 
can be used. 

The total number of cells is expressed per mm 3 . The isotonic diluting 
fluid keeps up the cells intact. In WBC counting, the solution will lyse the 
red blood cells and the remaining nucleated WBCs are counted. Venous 
blood is used in blood cells counting. 




~\ — 1 1 1 p i 



RBC pippette 



■ri i i i i i i i i r 



neubaur chamber 



Fig. 6.4.4. Counting chamber 
front and side views 



■,..*. 



WBC pippette 
Fig. 6.4.5. RBC & WBC counting pipettes 




i iiiumi 1 1 in 'i 



Fig. 6.4.6. Counting chambers 

240 



WBC chambers 



RBC chambers 



Normal Range of RBCs in human is as follows : 

Men : 4.5 - 5.9 million/mm 3 
Women : 4.1 - 5.1 million/mm 3 
At birth : 4.0 - 5.6 million/mm 3 

Normal Range of WBCs in human is as follows : 

Adults : 4,500 - 11,000/mm 3 
Neonates : 10,000 - 25,000/mm 3 

Clinical significance : 

1 . Decrease in the number of circulating erythrocytes indicates anaemia. 

2. An increased number of erythrocytes indicates the possibility of 
polycythemia. 

3. An increase in WBC count for a transient period indicates bacterial 
infection. 

4. Progressive increase in abnormal WBC count indicates the possibility of 
leukemia. 

4. Urine - Sugar analysis 

The examination of urine (pyhsical, chemical and microscopic) is called 
Urinalysis. It provides a valuable picture of the general health pattern of a 
patient. Urinalysis is usually done to 

(i) find out the state of the kidneys and the urinary tract, and 

(ii) gather information about metabolic and systemic abnormalities. 

To diagnose metabolic and systemic disorders such as diabetes and 
jaundice, tests for glucose, ketone bodies, bilirubin and urobilinogen should 
be carried out. 

Collection and preservation of Urine 

Urine is mainly composed of 95% water, and the rest being made of 
urea, uric acid, creatinine, sodium, potassium, chloride, calcium, phosphates 
etc. It must be collected in a clean, dry container and examined as soon as 
possible. For testing glucose, urine collected 2 to 3 hours after food is 
suitable. 

241 



Sugar Analysis 

Sugars are generally known as reducing substances because they can 
reduce a heavy metal, such as copper, from a higher to a lower oxidation 
state for example, the reduction of blue cupric sulphate to red cuprous oxide. 
Glucose, lactose, fructose, galactoese, pentoses, sucrose etc., are the 
reducing substances found in urine. Even though there are many reducing 
substances in the urine, estimation of glucose is important, as it indicates the 
hyperglycemic condition. 

Significance of Glucose 

Glucose is present in trace amonts in normal urine. In the kidneys, 
glucose is filtered by the glomeruli and reabsorbed by the tubules. Above a 
certain limit the tubules cannot reabsorb all the glucose. The surplus glucose 
appears in urine and this condition is known as glycosuria. When 
glycosuria is detected and hyperglycemia (excess glucose) is estalished, the 
chronic disorder, diabetes mellitus is indicated. In this condition as much 
as 280 milli moles/ L of glucose can be found in urine. It indicates 
disturbances in carbohydrate, lipid and protein metabolism. 

Urine glucose is tested both qualitatively and quantitatively. Benedicts 
test is the qualitative test to indicate the presence or absence of sugars. 
Different types of quantitative tests, each of them based on some principle 
are also employed to quantitate the urine sugar content. Some of them are 
Bendicts reagent method, glucose oxidase method ,o- toluidene method etc. 
Thin layer chromatography is considered a superior method for 
identification of urine sugars. Recently, digital glucometer is in usage for 
instantaneous determination of blood glucose levels. 

5. ECG-Electrocardiogram 

The electrocardiogram (ECG) is a record of the electric potential 
changes that occur in the heart during the cardiac cycle. It is recorded from 
the surface of the body. The instrument used to record the ECG is called 
Electrocardiogram. The waves of the ECG are due to depolarization and not 
due to contraction of the heart. This wave of depolarization occurs first 
before the contraction of the cardiac muscle begins. 



242 



The electrical activity of the heart was first recorded by Waller in 
1 887 with a capillary electrometer. But the work of Einthoven who recorded 
the ECG with a strong galvanometer only lead to the development of modern 
electrocardiography. Einthovan was awarded Nobel Prize in 1924. 

A normal ECG is composed of five waves designated from left to 
right with the letters P,Q,R,S and T. P,R and T are normally upward or 
positive waves while Q and S are downward or negative waves. 

ECG-'PQRST' wave 

When the cardiac impulse (originating in sinus node which is the 
primary pace maker) passes through the heart, electrical currents spread in 
the tissues surrounding the heart. A small amount of this current spreads to 
the surface of the body. If electrodes are placed on the skin on opposite 
sides of the heart, electric potentials generated by these currents can be 
recorded. This recording is known as electrocardiogram (ECGorEKG). 

P. Wave: It occurs in the auricles. It is an atrial wave. It is due to the 

spread of depolarisation in the atria (auricles). Its duration is 0.1 second and 
it occurs just before the atrial systole. Its amplitude is about 0. 1 to 0.3 mv.The 
cardiac impulse reaches the sinu- auricular node at about the summit of the 
Pwave. The P wave is a guide to the activity of atria. 

Q,R, and S Waves 




Fig. 6.4.7. Man with ECG leads attached 

243 



After the completion of P wave, the isoelectric interval occurs. 
Following this, QR and S waves begin. Q wave is a small negative 
downward deflection. It is mostly indistinct. It represents atrial septal 
depolarization. R wave is a prominent positive wave and S wave is a small 
negative wave. R and S are due to depolarization of the ventricular muscle. 
The duration of the QRS complex is about 0.08 second and usually does not 
exceed 0. 1 second. The average amplitude to R wave is about 1 mv. Lot of 
diagnostic information can be gained from alteration in the QRS complex. 

T wave 

Following S wave there is an isoelectric interval. T wave begins after 
that. It is due to ventricular repolarization. It is a broad wave. Its average 
duration is about 0.27 second and amplitude 0. 15 to 0.5 mv. 



1 ¥•:•:■■: ■■:: 



awa 




2-1 ---F rf.p.r.-a - O'Sseoard 









■vj 


4 








#^tl 






kL T ' 




:|o y 














■\"|: . IS 










I..: . 




4- 













Fig. 6.4.8. Graph of ECG 




Th« nonni flMctr^e-an-lK^a'^rn 



Fig. 6.4.9. Normal ECG 



244 



6. Computed Tomography (CT)(OR) Computerized axial tomography 
(CAT). 

The imaging technology or machine vision has revolutionized the 
medical world. It enables the doctors to watch vital organs, identify 
blockages and growths and diagnose signs of diseases without doing 
surgery. 

Computed tomography scan or (CT) scan : 

Comupted Tomography (CT) or "CAT scanning" combines the use 
of a digital computer together with a rotating X-ray device to create detailed 
cross sectional images or "slices' of the different organs. 

Advantages of CT over other imaging techniques 

Among the various imaging techniques CT has the unique ability to 
image a combination of soft tissue, bone, and blood vessels. For example, 
conventional x-ray image of the head can only show the dense bone 
structures of the skull. X-ray angiography of the head depicts only the head 
and neck and not the soft brain-tissue. Magnetic resonance (MR) imaging 
does an excellent job of showing soft tissue and blood vessels, but MRdoes 
not give as much details of bony structures such as the skull. CT images of 
the head allow physicians to see soft-tissues, anatomic structures like the 
brain's ventricles, of grey and white matter. CT can provide detailed cross 
sectional images and diagnostc information for nearly every part of 
the body. 

Uses of CT. 

1. CT is an invaluable tool in the cancer diagnosis process and is often the 
preferred method for diagnosing lung, liver and pancreas cancer. 

2. CT imaging and CT angiography are finding a greater role in the detection, 
diagnosis and treatment of heart disease, acute stroke and vascular diseases, 
which can lead to stroke, gangrene or kidney failure. 

3. CT can be used to measure bone mineral density for the detection of 
osteoporosis. 



245 



4. CT has excellent application in trauma cases and other internal bleeding in 
patients. 

5.CT is used extensively for diagnosing problems of the inner ears and 
sinuses. The anatomy of the inner ear and sinuses is made up of delicate soft 
tissue structures and very fine bones. CT is excellent for imaging tumors or 
polyps in the sinuses and disease that cause degeneration of the small bones 
in the inner ear. 

6. CT has been the basis for interventional work like CT guided biopsy and 
minimally invasive therapy. CT images are also used as basis for planning 
radiotherapy cancer treatment. CT is also often used to follow the course of 
cancer treatment to determine how the tumor is responding to treatment. 

7. Endoscopy (Laproscopy) techniques 

Endoscopy is a method of examining the interior of a body cavity or 
hollow organ (e.g., oesophagus, stomach) using an endoscope, a narrow, 
flexible fiber optic instrument that conducts light. Until recently, surgery was 
the most traditional of medical practices, employing techniques and 
instruments developed more than a century ago, but now patients have a 
new choice. 

Endoscopy is a minimally invasive approach to sugery of various parts 
It accomplishes traditional surgical goals while delivering less pain, faster 
recovery, and happier patients. The procedure does not require hospital 
admission and acute care and observation and may be performed outside 
the premises of a hospital. Outpatient procedures performed at hospitals or 
ambulatory centers allow the patient to go home or return to work within a 
short period while after endoscopic diagnosis. 

Types of Endoscopy 

1. Bronchoscopy: (trachea and lung's bronchial trees) 

2. Colonoscopy: (colon and large intestine) 

3. Colpscopy: (vagina and cervix) 



246 



4. Cystoscopy: (bladder,urethra, urinary tract, uteral orifices, and 
prostate (men) 

5. Gastroscopy: (Oesophagus, stomach,and intestine) 

6. Laryngoscopy: (larynx or voice box) 

7. Proctoscopy: (rectum and sigmoid colon) 

8. Thoracoscopy: (pleura, pleural spaces, mediastinum, and 
pericardium). 

9. Laparoscopy: (stomach, liver and other abdominal organs 
including the female reproductive organs, for example, the fallopian 
tubes.) 

10. Arthroscopy: (joints such as knee) 

8. Artificial Pacemaker 

A pacemaker is a small, battery-operated electronic device, which is 
inserted under the skin to help the heart to beat regularly and at an appropri- 
ate rate. The purpose of an artificial pacemaker is to stimulate the heart when 
either the heart's natural pacemaker is not fast enough or if there are blocks 
in the heart's electrical conduction system, preventing the propagation of 
electrical impulses from the natural pacemaker to the ventricles. 

Natural Pacemaker of heart 

The sinus node (sinoatrial node), (1 .5 cm long, 3mm wide muscle), 
situated on the right wall of the right atrium (auricle) where cadiac impulse is 
initiated. It is known as the natural pacemaker of mammalian heart, 

Componets of an Artificial Pacemaker 

A pacemaker generally has two parts, the generator and the leads. 
The generator contains the battery and the information to regulate the 
heartbeat. The leads are wires that go from the generator through a large 
vein to the heart, where the wires are anchored. The leads send the electrical 
impulse to the heart to tell it to beat. Most pacemakers run on lithium 
batteries. The battery can last for 7-8 years. It will be routinely monitored 

247 



by health care professional and replaced when necessary. The generators 
have become smaller over the years and often weigh less than 30 
grams. 

9. Autoanalyser 

To assist in the diagnaosis of diseases and disorders and to 
monitor therapy, a wide range of clinical tests has been developed. The 
demand for investigations is growing with the growing population and 
diseases. To get fast results on a large number of specimens, it is becoming 
inevitable to replace manual methods. This could be done by autoanalysers. 
With help of autoanalysers an increased work load can be processed rapidly 
and with reproducible results. To maintain the quailty of results, standards 
(samples of Known values) will be run along with every batch of test samples. 

Advantages of an autoanalyser : 

1 . Accuracy is more when compared with manual method. 

2. Large number of samples may be processed in minimal time. 

3. Two or more assays may be performed simultaneously. 

4. Calculations are not required. 
Disadvantages of an autoanalyser : 

1 . It is impractical for small number of specimens. 

2. Instruments may fail occasionally. 

3. Additional training of the staff about the working, maintenance and 
potential problems of the machine is needed. 

4. They are expensive. 

parameters to be analysed by an autoanalyser 

Autoanalyser can be used to estimate parameters such as glucose, 
protein, albumin, creatinine, blood urea nitrogen (BUN), sodium, potassium, 
chlorine, transaminase, lactic dehydrogenase, bilirubin, inorganic phosphate, 
calcium, cholesterol, uric acid, phosphatases and bicarbonate. 

248 



Apiculture 

Honey bees are social and polymorphic colonial insects .Honey bees 
provide honey, a high energy food supplement and wax which has almost 
unlimited uses. Cultivation of bees on a commercial scale for the production 
of honey is called apiculture or bee keeping .The beekeeping has been in 
practice for a very long time in India. Knowledge of biology, behaviour , 
diseases of bees and management practices are essential for beekeeping. 
Beekeeping is one of the more universal agricultural endeavours. Bees work 
a dual agricultural role by both producing honey and aiding in the pollination 
of flowering crops. Their cosmopolitan distribution, multipurpose nature and 
relative simplicity in managment combine to make bees a natural agricultural 
supplement for many types of farm system in developing countries. 

Advantages of beekeeping 

The advantages of beekeeping are: (1) It requires relatively low 
technology requirements (2) beekeeping basics are easy to master (3) low 
initial costs for set up (4) men, women, elderly and youth can participate 
(5) provides employment and self-esteem, (6) There is opportunity for quick 
return on investment (7) minimal land requirements (8) environmentally 
acceptable farming practice (9) promotion of greater viable food crop yield 
through bee pollination and (10) most bee products have a long self life and 
are a valuable food source. 

Types of Honey Bee 

Honey bee belongs to the class Insecta, order; Hymenoptera and 
family; Aphidae. There are five well recognised types of bees found in the 
world. 

1 . Apis dorsata (Rock bee) 

2. Apisflorea (little bee) 

3. Apis indica (Indian bee) 

4. Apis mellifica (European bee) 

5. Apis adamsoni (Africa) 

Out of these five types, Apis dorsata, Apis florea and Apis indica 

are common in India. 

249 



Apis dorsata : 

It is commonly called rock bee. It is a large Indian variety with an 
average size of about 20mm. It builds large comb (0.90 x 15metres) on tree 
branches, under caves, or under roofs of high buildings. A. dorsata 
undertakes migration during summer and winter. During winter they are 
abundantly found in plains and in summer the colonies 
migrate to high mountains to avoid extreme heat or in search of flowering 
plants. This species is a good honey gatherer. A sizable portion of honey 
produced in India comes from A. dorsata species. Maximum 50 to 80kg 
honey per colony can be obtained. 

Apis florea 

It is commonly called little bee. It is a miniature form of the rock bee. 
It lives in plains and it rarely occurs above 1000 feet of sea level. It builds 
small comb on the branches of trees, or in bushes, or under the walls of the 
buildings. The yield of honey from this species is very little. 

Apis indica 

It is popularly known as the Indian bee. It occurs commonly on the 
plains and forest of India. It builds several parallel combs in protected places 
like hollow of trees, caves, in rocks and in other such cavities. Their average 
output of honey is between 3kg to 5kg per colony per year. They are the 
best of the Indian variety to be hived in artificial conditions. 

Castes of Honey Bee 

Honey bee is a social insect. The nest of the honey bee is known as 
bee-hive. A hive in summer consists of 32 to 50 thousands individuals, 
depending on the locality. The members of honey bees are of three castes 
namely the queen bee, the worker bee and the drone bee. All the three 
types depend on each other for their existence. There is normally one queen, 
10,000 to 30,000 workers and few hundred drones in a colony. 

Queen Bee: 

There is only one queen in a honey bee colony. Queens are fertile 
females formed from a fertilized egg. It is slightly larger than a worker bee, 
with a longer abdomen. It does not have pollen baskets on her legs. Eggs 

250 




antenna 
leg 
eye 



wing 



abdomen 



Queen 




abdomen 



Drone 



antenna 



Fig.6.30. Honeybees 




abdomen 



destined to become queens are laid in a larger cell, and the larvae are fed 
only royal jelly. The royal jelly (bee milk ) is a salivary secretion of the 
worker bees. The adult queen's sole duty is to lay eggs, up to 2,000 a day. It 
is fed by the workers and never leaves the hive except to mate. Queen bees 
also have stings and use them in battles with each other for 
dominance of the colony. The life span of queen bee is 3-4 years. When the 
colony is crowded with adult bees, the queen leaves with a set of workers to 
establish new colonies and to promote propagation. This natural 
phenomenon is called swarming. 

Drones Bee : 

Drones are haploid fertile male because they develop 
parthenogenetically from unfertilized eggs. They are larger than workers and 
smaller than queen. They are quite noisy and unable to gather food. They are 
stingless and their sole biological function is to mate with queen. The number 
of drones in a colony varies from 200-300 but during unfavourable season 
they are driven out. 

Worker Bee : 

The vast majority of adult honey bees in any colony are female worker 
bees.The worker bees are sterile females. They have no individual existence 
throughout her life. They labours for the betterment of the colony. The 
functions of the worker bees are: tending and feeding young bees (larvae), 
making honey, making royal jelly and beebread to feed larvae, producing 
wax, cooling the hive by fanning wings, gathering and storing pollen, nectar 
and water, guarding the hive, building, cleaning and repairing the comb, and 
feeding and taking care of the queen and drones. 

Life cycle : 

The virgin queen bee mates once in her life. During breeding season 
of winter, a unique flight takes place by one queen followed by several drones. 
This flight is called "nuptial flight". The queen bee also produces a 
hormonal chemical substance called a pheromone. The drones in that area 
are attracted to the pheromone and then mating takes place. After mating 
she returns to the hive and lays eggs. Honey bees pass through four distinct 



252 



life stages namely the egg, larva, pupa and adult through metamorphosis. On 
the first day, the queen bee lays a single egg in each cell of the comb. The egg 
generally hatches into a larva on the fourth day. The larva is a legless grub 
that resembles a tiny white sausage. The larva is fed with a mixture of pollen 
and nectar called beebread. However , the queen forming larvae are fed on 
royal jelly for full larval life and they are taken for further development into a 
special chamber called queen's chamber. On the ninth day the cell is capped 
with wax by worker bees. Inside the cell larva spins a delicate silken cocoon 
around itself and the larva transforms into a pupa. The pupa is a physical 
transition stage between the amorphous larva and the hairy, winged adult. 
The pupa doesn't eat. Ultimately the adult comes out of cocoon. The queen, 
worker and drone bees take 16,21 and 24 days respectively for their 
complete development. 

Structure of a bee comb 




Honey Comb with worker bees 

Worker Cell Storage Cell 

1 000 v p(;.0- Drone Cei1 

Queen Cell After the &£rt/ Queen Cell 

Emergence of Bee >iJP 

A portion of the honey comb 
Fig.6.31. Honey comb 



253 



The comb of the bees are formed mainly by the secretion from the 
wax glands present in the abdomen of the worker bees. A comb is a vertical 
sheet of wax, with a double layer of hexagonal cells. The wax is masticated 
and mixed with the secretions of the cephalic glands to convert into a plastic 
resinous substance. The resinous chemical substance present in the wax is 
called propolis which is derived from pollen grains. 

The cells of the comb are of various types. The 'storage cells' 
contains honey and pollen. They are built in the margin and at the top of the 
comb. The brood cells contains the young stages of the honeybees and they 
are built in the centre and the lower part of the comb. Young ones of honey 
bees are collectively called brood. Brood chamber is divided into three types 
they are 

to rear the worker larvae developing into workers 
to rear the drone larvae developing in to drones, 
to rear the queen larva developing into queen. 

There is no special chamber for adults except queen. They move on 
the surface of the comb. 
Modern bee-hive structure 

Scientific method of bee - keeping has been developed after the 
extensive studies of bee behaviour, their way of functioning and their mode 
of reproduction. 

Top cover 

Inner cover 



Super chamber 



Worker-chamber 
Drone chamber 
Queen -chamber 




Brood chamber 



Bottom board 



Stand 



Fig.6.32.0uter view of a two-storey langstroth frame hive 

254 



Shelter made artificially for the bees to set up colonies is called 
bee-hive. The hive space must be large enough for passage of bees and 
smaller enough to discourage comb building. 

The modern beehive is movable-frame hive. It is a wooden frame box 
made of single or double walls. The single walled wooden frame box is used 
in warm place and the double walled wooden frame box is used in cool 
climate. A modern hive consists of a bottom board, brood chamber, 
supper chamber, inner cover and top cover. They are placed one above 
the other and fixed on a stand. All these parts can be dismantled. The 
bottom board acts as the entrance for the bees. The brood chamber is a 
wooden box inside which numerous frames called "comb foundations" are 
fixed. Comb foundations consist of sheets of pure bee wax. This wax sheets 
are embossed with the pattern of hexagons of a size equal to the base of 
natural brood cells. The worker bees secrete wax to extend the walls of 
these cells. The comb foundation helps in controlling the rise of the cells and 
reduces the number of drone cells. These frame of comb are movable and 
can be lifted, hence the name for the hive as "movable frame hive". 

The chamber above the brood chamber is the super chamber inside 
which honey is secreted and stored. Queen is prevented from entering this 
chamber by using queen excluder. This equipment has narrow spaces of 4mm 
which allows only the workers to enter the super chamber. The wooden 
board to cover the brood chamber or the super chamber is called inner 
cover. The top cover can be lifted to inspect the state of the colony or 
honey formation. The wooden hive is coloured yellow or white on the 
outside for keeping the chambers cool and to aid easy recognition by the 
bees. 

In India, apart from the modern hive, another three types of beehive 
namely Langstroth , Newton and Jeolikote are in practice. 

Other hive equipment : 

Besides the above primary equipments, other accessory equipments 
used in beekeeping and their utility are as follows. 

1 . Queen Excluder - it is utilized to prevent the entry of queen 

bee from the brood chamber into the super 
chamber. 

255 



2. Comb foundation 

3. Bee gloves 

4. Bee veil 

5. Smoker 

6. Hive Tool 

7. Uncapping knife 

8. Bee brush 

9. Queen introducing cage 



10. Feeder 



1 1 . Honey Extractor 



it is a sheet of bee wax and on both sides 
of which exact shape of different cells of 
the comb is made in advance. 

it is used by bee keepers for protecting 
their hands while inspecting the hives. 

it is a device made of fine nettings to 
protect the bee-keeper from bee sting. 

it is used to scare the bees during 

hive maintenance and honey collection by 

releasing smoke. 

it is a flat, narrow and long piece of 
iron which helps in scraping excess 
propolis or wax from hive parts. 

it is a long knife which helps in re 
moving the cap from the combs as 
a first step in honey extraction. 

it is a large brush often employed to 
brush off bees from honey combs 
particularly at the time of extraction. 

it is a pipe made of wire nets used 
for keeping the queen for about 24 hours 
for acquaintance with the hive and 
worker bees. 

it is a basin with sugar syrup covered by 
grass to feed the bees during drought 
season. The grass prevent the bees from 
sinking in to the syrup. 

it is a stainless steel device which 
spins the combs rapidly to extract 
honey. 



256 



12.Hive Entrance Guard 



it is a device similar to queen excluder 
in front of the hive entrance which 
prevents the escape of queen during 
warming season. 




' -frHHrflffM- 
7 
Fig.6.33. Queen excluder (Waldron) 




Fig.6.34.Comb - foundation 
fixed in a frame 



*=* cpwrr- 




Uncapping knife 
Fig.6.35. Hive equipments 

257 



Bee hive products : 

Some of the hive products are used for Apitherapy. The Apitherapy 
is the use of products from the bee to promote health and healing. 

Honey : Honey has been treasured as one of the nature's most perfect food. 
Other than honey, the products such as bee wax, bee venom, propolis, 
royal gelly and pollen are obtained as bee hive products. It is a sweet, 
viscous edible food obtained by honey bees. The colour, flavour and odour 
of honey usually depend on flowers from which nectar is gathered. It is an 
energy rich nourishing food. 

Chemical composition of honey 

The honey is composed of water, sugar, mineral like calcium, iron, 
phosphate, manganese and vitamins. Honey also contains acids, amino acids, 
enzymes, pigments and aroma substances. Besides, honey is an antiseptic 
and contains formic acid as the preservative. Honey is also used in all 
Ayurvedic and Unani Medicines. Honey is a good laxative and a blood purifier. 
It prevents cough and cold and also relieves sore throat. Honey is a remedy 
for tongue ulcer and intestinal ulcer. Honey is made into alcoholic drinks by 
fermentation. These drinks are popularly known as mead or honey wines. 
Large amounts are used in skin and beauty lotions. 

Bee wax : Wax derived from bee hive are utilised as follows: 

1 . Bee wax is used in candle industry and bee industry for preparing comb 
foundation sheets. 

2. Wax is an important constituent of cosmetics like cold creams, lipsticks 
and rouges because it adheres better to skin. 

3. Pharmaceutical and perfume industries are also major users of wax. 

4. It is also used in ointments, capsules, pill coatings and deodorants. 

5. Wax is used for preparing shoe polish, furniture, etc. because it acts as 
waterproofing. 

6. Its minor use is made in adhesive, chewing gums ink etc. 



258 



Bee Venom 

Sting of worker bee is attached to a poison sac where venom is 
stored. It is composed of many substances such as histamine, apamine, 
acithinase, hydrocholoric acid, formic acid, orthophosphotic acid, sulphur, 
calcium, copper and magnesium sulphate. 

1 . Apitherapy : Bees can be made to sting the patient who has skin disease 
and the venom collected can be used as medicines for subcutaneous infections. 

2. Ointment made by mixing apitoxin, vaseline and salicylic acid can be 
used to make the skin soft and increases penetration. 

3. Bee venom is useful for curing many diseases and disorders especially 
Rheumatism. 

4. It has stimulating effect on heart muscles. It decreases cholesterol level 
and also lowers blood pressure. 

5. It is used in the treatment of neurosis, arteriosis and arthritis. 

Propolis (Bee glue) 

Propolis is gathered by bees from resinous exudes of trees. Propolis 
is mainly composed of resins and balsams, ethanol, scented oils and pollen. 

1 . Propolis is used by bees for sticking frames, sealing cracks and crevices. 

2. As it is a natural effective antibiotics, it is useful in preparing ointments for 
healing cuts, wounds and abscesses in cattle. 

3. It is used in cosmetics 

4. Propolis is sold as supplement in health shops too in the form of capsules, 
tablets and in liquids. 

Royal jelly (Bee milk) 

Royal jelly is secreted by glands of nurse bees of the age of 6- 1 2 
days. It is very nutritious food and is fed to the young larvae and adult queen. 
Royal jelly is milky white in colour. It is composed of protein, lipids, 
carbohydrates, water and ash. Royal jelly is a nutrious food for human beings 
as it increases vigour and vitality. 

259 



Pollen: 

The worker bees (field bees) collect pollen, which is the basic form 
of renewing species of plants as well as feeding the hive larva as well. The 
nurse bees of the hive will refine the pollen in to beebread or royal jelly for 
feeding to larva and young bees. Pollen is also used for human consumption 
since it's packed with 25 protein and 18 amino acids. 

Diseases of bees and their enemies 

Honey bees are affected by large number of viral, fungal, bacterial 
and protozoan organisms, ecto-endo - parasitic mites, insects and non-insect 
enemies. 

Viral diseases 

Sac brood : It is caused by a virus and found in 30% of this colony. This 
prevents larvae from pupating. 

Kashmir bee viruses : This disease will affect in all stages of development 
Infected bees die in the affected colony. 

Fungal diseases 

Chalk brood : Caused by a fungus. Strands of fungus invade the larvae 
tissue and the larvae dies. The dead larvae become chalky white in colour. 

Bacterial diseases 

American foul brood (AFB): Caused by spore forming bacterium. This 
bacterium penetrates the gut wall and body tissue of the larvae. Infected 
larvae change colour from a healthy pearly white to dark brown and die after 
they are capped. 

Protozoan diseases 

Nosema : Caused by spore forming protozoa. It impairs the digestion and 
cause dysentry. 



260 



Acarine disease 

"Isle of wight" - an acarine disease caused by a small parasitic mite 
due to the blocking of the trachea of bee. Infestation of this mite causes 
chronic bee paralysis. 

Enemies 

There are a large number of animals who act as enemies to the bee. 
Some of the enemies are wax moth, wax beetle, tods, snails, ants, dragon 
flies, praying mantis, termites etc. 

Present position of apiculture industry in India 

The number of bee colonies in India at present is about 5.75 lakhs 
irrespective of our goal of establishing 15 crores bee colonies. In Maharashtra, 
regular bee farms have been established at several places. Among the honey 
producing States, Tamil Nadu stands first followed by Kerala and Karnataka 
respectively. 

Bee research centers have been established at several places in India. 
The Indian Council of Agricultural Research is engaged in research and 
developmental efforts in various disciplines of agriculture including api-culture. 

Sericulture 

The silk is used for various purposes since ancient times. Pure silk is 
one of the finest natural fibre and is said to be the "queen of fibres". Due to 
its great value and usefulness, various methods were adopted to rear silk 
worms on a large scale with great care. Rearing of silkworm and adoption of 
different rearing techniques for the production of silk threads of fine quality is 
known as Sericulture. 

Types of Silk. 

The silk is produced by certain moths. The moths belonging to the 
families Saturnidae and Bombycidae of order Lepidoptera and class 
Insecta. Mainly four types of silks have been recognized which are secreted 
by different species of silkworm. 



261 



(1) Mulberry Silk : This silk is superior in quality due to its shining and 
creamy white colour. It is secreted by the caterpillar of Bombyx mori, which 
feeds on mulberry leaves. 

(2) Tasar Silk : It is secreted by the caterpillars of Antheraea mylitta, 
A.paphia, A.royeli etc. This silk is of coppery colour. The caterpillars feed 
on leaves of Arjun, Asan, Sal, Oak . 

(3) Eri Silk : It is produced by the caterpillars of Attacus ricini which feed 
on castor leaves. Its colour is creamy white like mulberry silk and is less 
shining than the latter. 

(4) Munga Silk : It is obtained from caterpillars of Antheraea assama, 
which feeds on leaves of Som, Champa and Moyankuri. It is shining like 
tasar silk. 

Type of silk Type of silk insect 

1 . Mulberry Bombyx mori 

2. Tasar Antheraea mylitta 

Antheraea paphia 
Antheraea ray eli 
Antheraea pernyi 

3. Eri Attacus ricini 

4. Munga Antheraea assama 



Food plants 

Moras alba (Mulberry) 

Arjun 
Asan 
Sal 
Plum 

Castor 

Champa, Som, Moyankuri 



Biology of silk moth 

The domestic Silk Moth, Bombyx mori, is a member of a small 
family of about 300 moth species in the Order Lepidoptera. Adults of this 
family have heavy, rounded, furry bodies and cannot feed because of 
undeveloped mouth parts. It is a flightless insect. Wings and body are 
usually white, but may vary to shades of light brown. 

Wingspan is 4-6 cm. Wings are membranous and weak. The adult 
moths have a very short life, and live only for 2 or 3 days after emergence. 

The larva of Bombyx mori is an elongated caterpillar commonly called 
a silkworm. Larvae are monophagous and feed only on mulberry plants. The 
larva will moult five times before spinning a silk cocoon of one continuous 
fiber for pupation. Silk cocoons from this species are the commercial source 
of silk. 



262 



Formation of silk: 

Silk is the result of secretion of silk glands (modified salivary gland). 
There are two long tubular, coiled glands lying one on each side of the 
alimentary canal of the caterpillar. These glands are connected to a narrow 
tube like structure known as spinneret. The spinneret is a part of the 
hypopharynx (tongue). Fibroin, a sort of liquid fibrous protein is secreted 
by the silk gland. It is insoluble in water and is made up of glycine, alanine 
and tyrosin. As the liquid secretions of the two glands pass through the 
Spinnert, it transforms them into a single thread. Sericin, another secretion 
produced by a pair of accessory glands, cause the two fibers of fibroin to 
unite. Two streams of fibroin along with sericin are expelled through the 
spinnert due to contraction and expansion of the body of the caterpillar. This 
sticky secretion when comes into contact with the air is converted into a fine, 
long and solid thread of silk. 

Life cycle : 

The life cycle of Bombyx mori has four distinct stages . They are 
egg, larva, pupa and imago. 

Stage 1 - EGG: Incubation 7-10 days 

The egg of Bombyx mori is a very small and hard structure about the 
size of a pin head and resembling a poppy seed. The egg shell provides a 
protective covering for embryonic development. When the eggs are first laid, 
they are light yellow in colour and later the eggs become darken to a 
blue-grey within a few days. 

Stage 2 - Larva: 45 days (5 instars) 

The larva is the vegetative stage where growth takes place. The larva 
of Bombyx mori, commonly called a silkworm, ( caterpillars) . During 
growth, the larva moults four times. The period between successive moults is 
called an instar.The caterpillars have segmented appearance with strong 
mandibular jaws. Throughout the five instars the larva keeps on consuming 
the mulberry leaves .The salivary glands (silk glands)are fully grown and silk 
concentrate gets secreted out of this gland. 



263 




Mature Caterpillar 
6.36. Life-cycle of mulbery silk-moth 

Stage 3 - Pupa : 15 days 

The secreted silk spins in to a silk cocoon. The silk cocoon serves 
as protection for the pupa. Cocoons are shades of white, cream or yellow in 
colour. After a final moult inside the cocoon, the larva develops into the brown, 
chitin covered structure called the pupa. Metamorphic changes of the pupa 
result in an emerging moth. 

Stage 4 - Imago: 5 - 7 days 

An adult insect produced after metamorphosis is called imago .This 
adult stage completes the life cycle of Bombyx mori. It is the reproductive 
stage where adults mate and females lay eggs. Moths are flightless and lack 
functional mouth parts, so they are unable to consume nutrition. 

Sericulture in Mulberry Type: 

Mulberry silk worms are of domesticated type because they can be 
reared indoors. Large and healthy cocoons are selected and they are kept in 
well ventilated cages. Young ones emerge after few days and male and 
females are easily distinguished. Females are larger than males. Once they 
attain maturity, they are kept as pairs in the coupling jars for about 24 hours. 
After copulation females are transferred to egg-laying boxes. Each female 
lays about 300 - 400 eggs of small size. These eggs are commercially called 
seeds. A great care should be taken in the selection of seeds because the 
quality of the seeds depends on the silk production. The eggs are kept in 
incubators at 70°F. Small larvae hatch between 7-10 days, and they are 
known as caterpillars. 

264 



The sericulture practice involves three different stages. They 
are (1) Cultivation of food plants(Plant origin) (2) Rearing of larvae (Animal 
origin) and (3) Reeling of thread from cocoon (Technical origin). 

Cultivation of food plant - Stage 1 

The larvae of Bombyx mori feed on leaves of mulberry. Regular 
supply of healthy mulberry leaves is essential. Mulbery leaves have high food 
value. It is a perenial woody plant. Mulbery trees can be propagated by 
sapling, cutting and grafting methods. 

Rearing of larvae tiny caterpillars - Stage 2 

Initially the caterpillars measure 5-7 mm in length. They are 
transferred to feeding trays containing chopped tender leaves of mulberry. 
They start feeding on the tender leaves and grow faster. The caterpillar thus 
formed stop feeding and become inactive within four to five days. The larvae 
then undergo morphological changes after every moult. They undergo 5 moults. 
The maturity is achieved in about 45 days. The salivary glands, otherwise 
called silk glands start secreting silk. 

At this stage, the matured caterpillars are transferred to spinning trays. 
They excrete their last excreta and begin to secrete sticky secretion from the 
silk glands through a very narrow pore situated on the hypopharynx. With in 
5 days, the caterpillars are transformed into pupa or cocoon. After 15 days 
acute metamorphic changes take place during pupation and the young imago 
tries to come out. The young one secretes an alkaline fluid to soften one end 
of the cocoon. Later it escapes by forcing its way out of the softened area. 
Just after the formation of cocoons, healthy cocoons are selected and kept in 
cages for the next crop. 

Tools and materials necessary for rearing Silk Worms. 

House : A well aerated building or mud walled thatched houses are the best 
as they are cool in summer and warm in winter. The optimum temperature for 
maintaining larvae is 70° -75°F. 

Feeding Trays: Freshly hatched worms are kept in flat trays made up of 
bamboos along with small pieces of mulberry leaves. 

265 



Machan : Machan are made by fixing two pairs of bamboos in the ground 
and tying across bars of bamboos. They are needed to accommodate large 
number of trays in a limited space. 

Nets : Large amount of excreta, dirty products and remains of leaves may 
fall on the trays from the holes of the upper trays. If worms are not protected 
from these wastes they may get diseased. To prevent this, trays are covered 
with the nets. 

Spinning Trays : Before cocoon formation mature worms are transferred 
to specific type of trays known as spinning trays or Chandraki. 

Initially the start of rearing the machan, feeding trays, spinning trays, 
nets and everything used in rearing except the leaves are washed with 
Copper sulphate solution or other antiseptic chemicals. The remaining germs 
are killed by fumigation. 

Precautions to be taken during rearing of mulberry silkworms. 

1) The worms should never be kept, over crowded in a tray. 

2) Dried or dusty leaves should never be fed to the worms. 

3) Free ventilation is a must. 

4) There should be equal distribution of leaves among the worms. 

5) Worms which are under process of moulting should not be disturbed. 

6) There should be no dust at the floor of the house. It should be well 
plastered with cow dung or mud at regular intervals. 

7) Smoking should be strictly prohibited in the rearing room. 

8) Worms should not be handled with dirty hands to avoid infection. 
Hand should be washed before handling. 

9) Water may be sprinkled periodically over the feeding trays, during the hot 
season. 

Stage 3 -Reeling of raw silk from cocoon 

For the production of standard variety of raw silk latest technology is 
employed for the speedy and economical reeling of raw silk. 
Reeling process is an important aspect of sericulture because cocoon 
production is directly related to reeling industries. 

266 



Before reeling the thread, the cocoons are dipped in a container of 
hot water for more than 10 minutes. During this period, continuous stirring 
with a rod is necessary. Due to this, their outer portion is loosened and 
removed in the form of long tapes. The end of the continuous filament is now 
found. The filaments of several cocoons are picked up and passed through 
the 'glass eye' on to the reel. The thread thus reeled forms the "raw silk" of 
commerce. About 1 kg of raw silk is obtained from nearly 55,000 Cocoons. 

Uses of Silk : 

1 ) Silk fibers are utilized in preparing silk clothes. Silk fibers are now 
combined with other natural or synthetic fibers to manufacture clothes like 
Tere-Silk, Cot-Silk etc. 2) Silk is used in industries and for military 
purposes. 3) It is used in the manufacture of fishing fibers; parachutes, 
cartridge bags, insulation coils for telephone and wireless receivers, tyres of 
racing cars, filter clothes, in medical dressings and as suture materials. 

Diseases and enemies of silk worm 

The profitable silk industry is threatened not only by various diseases 
caused by the virus, fungal, bacterial and protozoan infections but also by 
insect predators, birds and other higher animals. Ants, crows, kites, rats, 
feed upon silk worms thereby causing a great loss to silk industry. Various 
types of silk worm diseases, the symptoms and methods of control have 
been given in the following chart. 



Name of 


Infecting 


Symptoms of 


Controlling methods 


disease 


agent 


disease 




Pebrine 


Protozoan 


Death of under 


Treatment of eggs 






nourished larvae, 


transmitted through with 






Porductionof 


water (47°C) or rejection 






lesser silk, 


of infected and 






death of larvae. 


defective eggs. 


Flacherie 


Bacterial 


Softening of 


Careful rearing in 




infection 


skin and 


healthy 






physical 


conditions. 






disability. 





267 



Grassarie 


Viral 


Moulting is 


General cleanlines, 




infection 


affected, skin becomes 


separation 






yellow and blood 


of affected worms and 






becomes milky, 


immediate disposal of 






putrificationof 


dead worms. 






internal organs and 








death of larvae 




Muscardine 


Fungal 


Worms body 


Maintenance of stock 




infection 


becomes 


which are resistant to 






hard 


the disease and by 
using disinfectants. 



Sericultre in India: 

India stands fifth in the production of silk. The other main silk 
producing countries in the order of production are Japan, China, South 
Korea, USSR, Brazil, Bulgaria and Italy. India accounts for 5% of the total 
global output of mulberry raw silk and 10% of Tasar. The production of 
natural silk has increased to about 40% in the last 15 years and the global 
output of 1974 was 45 thousand tones. At present the production rate is 
higher and the value of silk product in India is about Rs. 80 crores per 
annum. 

In India the major silk producing states are Mysore, West Bengal, 
Jammu and Kashmir, Assam, Bihar, Orissa, Madhyapradesh, Uttra Pradesh, 
Andhra Pradesh, Tamil nadu, Punjab, Manipr, Tripura and Maharashtra. 76% 
of total production of raw silk is in Mysore. Mulberry silk is restricted in 
Purnea district along the border of West Bengal. Bihar has the privilege of 
producing Tasar in larger quantity. The Eri silk is limited in the state at Gangetic 
plains (Assam & Bihar). Munga silk is produced only in Assam. 

Rearing of silk worms on a large scale is carried on in villages and 
remote forests by villagers and tribals. They are assisted by State 
Government and Central Government agencies. A qualitative and 
quantitative breakthrough has been made by "Central Silk Board" running 
under the Union Ministry of Trade and Commerce. The increased silk 
production in India is due to research conducted on various aspects of the 

268 



industry by the respective research centres running under this board. The 
important research centres are the following, 

(1) Central Sericulture Research Station - Berhampur, West Bengal 
(Mulberry). 

(2) Sericulture Research Institute Channapatna - Mysore (Mulberry). 

(3) Central Munga and Eri Research Station - Titabar - Assam. 

(4) Central Tasar Research Station - Ranchi, Bihar. 

These research stations have sub-stations and extension centres in 
different parts of the country for the convenience of the sericulturists in 
remote areas. 



269 



7. THEORIES OF EVOLUTION 

Introduction 

Several opinions had been made available to explain the origin and 
existence of various forms of life. The existing living beings show characteristic 
resemblances in form and functions. There are evidences for succession of 
several types of living organisms occupying earth. Populations of animals 
and Plants tend to undergo predictable changes in their population 
intensities. An explanation to all these interesting natural happenings had been 
attempted through various modern theories of evolution. An initiation for such 
evolutionary thought process was well provided by Lamarck. This 
evolutionary theorizing culminates in the modern synthetic theory of 
evolution afforded by different fields in biology. 

Lamarckism 

Jean Baptiste de Lamarck ( 1744 - 1 829) is well known for his theory 
of evolution. In 1809 he published his book titled 'Philosophic Zoologique' . 
This book contains his views on evolutionary mechanisms. Eventhough the 
views of Lamarck are not fully accepted, he occupies a very important place 
in the history of evolutionary thought. 

The theory of evolution as proposed by Lamarck is popularly known 
as the ' theory of inheritance of acquired characters ' . According to thi s theory 
modifications or changes acquired during the life time of an organism can 
automatically be transmitted to succeeding generations. While elaborating 
this theory, Lamarck advanced four laws or propositions. 

I Law (or) Proposition 

'In evolution, during course of time, organisms or their 
component parts gradually tend to increase in size. 

Lamarck cited the evolution of horses as an example to 
explain this law. The modern horses, namely, Equus evolved from very small 
ancestral forms called Hyracotherium or Eohippus. Such small forms 
survived years ago. They gradually evolved into larger modern Equus. 

270 



Lamarck's opinion was based on fossils of several intermediate ancestors of 
horses. Whose fossils had already been discovered. However during recent 
years various other fossils had been obtained. Of these fossils, some of them 
are much smaller than their immediate ancestors. This finding is against the 
view already expresed by Lamarck. Thus the first law of Lamarck lost its 
significance. 

II Law or Proposition 



'If an organism is 'in need' of an organ, sooner or later it will 



arise. 



This view of Lamarck emphasized the significance of mind and its 
thinking being related to needs in an environment. Thus, according to Lamarck 
a continuous thinking for several generations can lead to the origin of an 
adaptive character. Lamarck elaborated his view citing the lengthening of 
neck in giraffee over the years. 










Fig. 7.1.Lamarck's Theory 



It is known through fossil records that the ancestors of modern 
giraffe were small and they had short neck and forelimbs. They lived in the 
grasslands of Africa. These ancestral animals were feeding on grasses and 
the leaves of small trees nearby. Gradually, as the grasslands were 
transformed into deserts, the animals became dependent on trees for food. 
Due to competition for food they had to stretch their neck for more leaves. 
They strained their neck for several generations with a very strong inner 
feeling to have longer neck. This strong desire, in course of time, led to gradual 
increase in the length of neck and forelimbs. 

271 



In this explanation Lamarck considered that mere 'want' or 'inner 
feeling' to possess a particular character can lead to the 
origin of such a character. This view of Lamarck is not accepted by modern 
evolutionists. 

III Law (or) Proposition - Law of use and disuse 

According to this law, constant use of an organ changes its 
efficiency and makes that organ to increase in size with better development. 
Similarly if an organ is not used for a long time, it might lead to reduction in 
efficiency and size of that organ. The development of hand muscles of a 
blacksmith and thigh muscles in the legs of an experienced runner were 
quoted as examples. Eventhough this view of Lamarck is correct and 
acceptable, it is not relevant to evolution due to lack of inheritance. 

IV Law (or) Proposition. Inheritance of Acquired Characters 

'Bodily changes or new charateristics obtained by an 
organism during its life time will automatically get transferred to the 
next generation \ 

While proposing this law, Lamarck did not provide any 
specific example. He simply believed that due to conditions prevalent in an 
environment, an organism can use an organ extensively and such an usage 
can lead to more efficient and perfect nature of that organ. Similarly, an organ 
not used for a longer period would degenerate. These perfect or degenerate 
characteristics will be inherited by subsequent generations resulting in new 
types. 

The IV Law of Lamarck had been subjected to severe 
criticisms. Several experiments had been carried out, either to prove or 
disprove this concept. 

In 1 890, the German Scientist, August Weismann performed some 
experiments with the rats. He selected a set of healthy male and female rats. 
He started cutting their tails continually for more than twenty generations. 
This experiment was performed to verify inheritance of the acquired 
character, namely the tailless condition. Interestingly such a condition was 
never observed in any of the young rats born. This finding led to the 
proposition of the theory, that any change to the body regions (somatoplasm) 

272 



will not have influence over the reproductive cells (Germplasm). Thus 
Weismann, for the first time segregated germplasm from the somatoplasm. 

This lead to the formulation of the 'Germplasm theory' which states 
that 'any change to the somatoplam will not have an influence over 
the germplasm \ 

Neo-lamarckism 

Lamarck's 'theory of inhertitance' was further studied by a group of 
scientists. Their ideas supporting Lamarck's opinion collectively constitute 
neo-Lamarckism. 

The neo-Lamarckians were of the opinion that 'adaptions' are 
universal in nature. An adaptation happens through causal relationship of 
structure, function and environment. Due to changes in the environment, habits 
and life style of organism gets altered. Thus gradually the organism acquires 
new structures. The newly obtained character gradually becomes an 
inheritable trait. This opinion and argument is a modified form of 
Lamarckism. These ideas stressed direct action of environment on organisms. 

Support to neo-Lamarckian concept - Experiments 

1 . McDougall (1938) tried to prove that learning is an acquired character 
that can be inherited. He did his experiments on rats. 

He deviced a 'T' shaped tank. The tank had two exits. One exit was 
well lighted. However at the terminal region of the exit he deviced an 
arrangement for giving electrical shock. The pathway to the other exit was 
kept dark. At the terminal exit point a small piece of cheese was kept as a 
reward. McDougall dropped several rats into the tank. Many of the rats 
preferred lighted pathway to escape and at the exit they received electric 
shock. Those rats, that preferred dark pathway received the cheese. He 
repeated the trial several times. Gradually many rats learnt the correct route 
for escape. Subsequently the rats were allowed to breed and the next 
generation developed. 

The same experiment was repeated in the second generation. 
According to Mc Dougall, it was claimed that the number of mistakes 
committed, gradually got reduced. The speed of learning increased from 

273 



generation to generation. Thus he concluded that learning is an acquired 
character. 

However later workers found some technical mistakes in the work 
of Mc Dougall. The same experiment while repeated in other laboratories 
failed to give similar results. 

2. Temperature related changes in the body of mice was noted by F.B.Sumner 
(1910). He reared one set of white mice in warmer temperature (20 - 30°c) 
and another set in cold conditions. He found that in warmer conditions the 
mice developed larger ears and longer tails. He further claimed that these 
characters were inherited. 

Through similar works claim for inheritance of acquired characters 
were made by Lindsey, Guyer and Smith and Kammerer. In all these works 
while repeating, critics have found technical mistakes and rejected them 
outright. 

However, the controversy over 'inheritance' of acquired characters 
still continues. This theory of Lamarck while has not been disproved totally, 
it remains to be proved correct. 

Darwinism 




Fig. 7.2.Charles Robert Darwin 

Darwinism comprises the natural selection concept as advanced by 
Charles Robert Darwin in 1859. His theory provided the correct idea to 
explain all processes and intricate mechanisms of evolution. The theory of 
natural selection is considered on par with Newton's law of gravitation and 
Einstein's theory of relativity. The monumental work of Darwin was titled as 
"The Origin of species" (the original full title of the book was 'On the Origin 

274 



of species by means of Natural Selection, or the Preservation of favoured 
Races in the struggle for life'). 

The book of Darwin convincingly demonstrates the fact of 
evolution. Further, it elaborates on the theory of natural selection as a 
convincing mechanism for providing evolutionary transformations. 

Charles Darwin was born in Shrewsbury, England on February 12, 
1809. While studying in college at England through his friendship with 
Professor J.S. Henslow, Darwin became familiar with Botany. Later he 
accepted the job of a naturalist aboard the ship H.M.S Beagle. The ship was 
to spend five years, in exploration around South America (1 829 - 34). 

During the period of five years, Darwin visited pacific islands and 
many parts of the world. He returned to England in 1836. Later he worked 
for a further period of 20 years to develop his theory of natural selection. 
While Darwin prepared his work for publication, a similar idea to explain 
evolution was proposed by another naturalist, Alfred Russel Wallace 
(1823-1913) from Malay archipelago. Charles Darwin gracefully accepted 
for the publication of his theory as a joint paper with Wallace. Thus the theory 
of natural selection is actually titled as 'Darwin-Wallace theory of 
evolution' . 

The Theory of Natural Selection 

During his period of study Darwin has made several observations 
and collected facts. Through these facts he arrived at certain conclusions. 
These conclusions constitute Darwinism. Thus Darwinism or the theory of 
Natural selection includes the following elements. 

1. Overproduction or Prodigality of nature 

All living beings have an innate desire to reproduce and form their 
own progeny. In this attempt they have the capacity to multiply in a 
geometrical manner. Such an enormous reproductive potentiality can be 
observed in all species of organisms. For example a single female salmon fish 
can produce 28,000,000 eggs in a season. A common oyster of the Atlantic 
coast may release as many as 80 million eggs in one season. At the time of 
breeding the ovaries of a cod fish may contain 10 million eggs. If natural 

275 



processes of reproduction are allowed without any check a single pair of 
English sparrows can produce 275 billion descendents in 10 years. The 
elephants are the slowest breeders. An elephant begins to breed at 30 years 
of age. It goes on breeding till it is 90 years old. A female elephant can give 
birth to 6 young ones during its life time. Under these conditions, a pair of 
male and female elephants can cause the production of 19 million elephants 
in 750 years. Thus, the reproductive capacity is an innate nature of living 
organisms. 

2. Struggle for existence 

According to Darwin while the population increases in geometric 
ratio there is no corresponding increase in food production. This causes an 
intensive struggle for living. The struggle happens for food, space for 
living and for coping with environmental conditions. The struggle may be 
intraspecific or interspecific. In an intraspecific struggle there is a 
competition among the individuals of the same species. Such a struggle is 
severe because the needs of the competing organisms are identical. Struggle 
might happen with environment too. Conditions like heat, cold, drought, 
storms, floods and other natural changes can affect organisms resulting in 
struggle for existence. 

3. The universal occurrence of variations 

The occurrence of variations is a characteristic feature of all groups 
of animals and plants. The variations may be morphological , anatomical, 
physiological or behavioral. (However during Darwin's time the actual cause 
and nature of variations were not known). 

As a result of variations, no two animals would look alike. Even the 
progeny of the same parents are not exactly alike in all respects. Eventhough 
variations are universal all such variations need not be significant from an 
evolutionary point of view. Certain variations that get established in the 
population and get inherited continually are termed, heritable variations. 
Such variations form the raw material for evolution. 

4. Survival of the fittest 

While all living organisms face the struggle for existence, certain 
organisms possessing adequate modifications are able to escape and 

276 



survive. Such modifications are due to inherent variations. Hence favourable 
variations make an animal or a plant to be successful in life. They survive as 
fittest organisms in an environment which gets altered frequently. 

5. Natural Selection 

According to Darwin 'the fittest' forms that are allowed to survive 
are chosen by 'Natural Selection' (an imaginative concept which includes all 
real aspects of the natural environment that supports the life of 
organisms). 

The forces of natural selection will encourage only those that have 
suitable variations as adaptive features, to survive. Darwin designated them 
as 'fittest' forms. All other organisms having non adaptive or deleterious 
modifications shall be disqualified. Natural selection will eliminate such 
organisms from the populations. The selected group of modified 
individuals will occupy the next level in the evolutionary ladder. 

Darwin strongly believed that using the natural selection concept, all 
evolutionary processes in the living world can be explained. As an 
example he differed from the explanation provided by Lamarck while 
explaining the lengthening of neck in giraffe. According to Darwin the 
population of giraffes had individuals having varying neck lengths. Those that 
had longer necks had more survival value, since they had more food and 
remained healthy. Gradually natural selection encouraged them to 
survive. Thus in course of time the average length of the neck increased. 

Objections to Darwinism 

While the ideas of Darwin, related to reproductive capability, 
prevalence of variations, concept of struggle and survival of suitable forms 
are all commonly accepted, there are certain drawbacks in his original theory. 

1 . Darwin could not explain, the origin and cause for variations while insist- 
ing their importance in progressive evolution. 

2. He overemphasized the importance of the 'fittest' organisms. During later 
periods it has been suggested that 'fit' and fitter forms can also exist along 
with the fittest. 



277 



3. As the principle of inheritance as explained in the later years were not 
available during Darwin's time. Hence he believed in the theory of 
'pangenesis' . According to this concept from every organ in the body very 
minute such replicate structures will orginate. Later they are transferred to 
the gonads for transmission to future generations. 

4. 'Over-specialization' as in Irish deer and its consequent harmful effect on 
animals had not been accounted for by Darwin. 

Neo-Darwinism 

A modified form of Darwinism is known as neo-Darwinism. It was 
developed due to acceptance of Darwinism and provision of several 
evidences in support of Natural Selection concept. The early 
neo-Darwinians were T.H. Huxley of England, Asa Gray of United States 
and E.Haeckel of Germany. 

The neo-Darwinians differentiated the germplasm from somatoplasm 
and proposed the 'germplasm concept' . They also belived that characters 
are due to certain factors called the determinants that control the 
development. The neo-Darwinism concept was incomplete and erroneous. 
It lacked in an understanding of genetics as it is known in later periods. 

Modern concept of Natural Selection (or) Modern synthetic theory of 
Evolution. 

Modern development in biological fields such as Cell biology, 
Genetics and Populations genetics helped in the development of modern 
synthetic theory of evolution. It was caused due to contributions made by 
eminent scientists such as Th. Dobzhansky, S.Wright, H.J.Muller, J.S. Huxley, 
R.A.Fisher, Ernst Mayr, GL.Stebbins and others. 

The basic concept of modern synthetic theory was provided by Th. 
Dobzhansky in his book titled "Genetics and the Origin of species" (1937) 
G.L.Stebbins in his book "Process of organic evolution" (1971) suggests 
five basic processes essential for evolution. They are gene mutations, 
chromosomal aberrations, genetic recombinations, natural selection 
and reproductive isolation. Contributions made by others provided 
additional factors such as Hardy-Weinberg equilibrium, Genetic drift and 
Polymorphism. 

278 



1. Gene Mutations 

Since proteins perform several functions, they determine many of the 
characteristics of organisms. The role played by a protein is largely 
determined by its primary structure. The primary structure is due to the 
sequence of amino acids in its molecule. This structure in turn determines the 
three dimensional protein molecule. The conformation determines the 
protein function. 

The basic sequence of amino acids in proteins is precisely regulated 
by the genetic code. Any change in the code due to gene mutation will result 
in the production of abnormal proteins. The abnormal proteins thus formed 
may be either beneficial or harmful. A gene producing a beneficial protein 
confers an advantage on its possessor. Gradually its frequency increases in a 
population. Individuals having harmful mutations may not survive to 
reproductive age. So, such mutated genes are not passed to the next 
generation. 

The mutations are considered as the 'raw materials' for evolution. 
They help to create and provide variations in a population along with genetic 
recombinations. The collection of genes in a population is referred to as the 
'gene pool' . Mutations enrich the gene pool with new modified genes. A 
large scale accumulation of such genes will lead to evolutionary 
modifications. 

2. Chromosomal aberrations 

During the process of meiosis one or more chromosomes may break. 
Such broken fragments of chromosomes may be subjected to several 
modified organizations : 

a) a small broken fragment may become lost (deletion) 

b) the broken fragment may become attached to the end of another 
chromosome (translocation) 

c) the fragment may become turned around and rejoin the chromosome 
(inversion) 

d) they may become inserted into another chromosome (duplication) 

All the above mentioned changes may alter the genomes of gametes. 

279 



Sometimes a pair of homologous chromosomes may fail to separate 
in meiosis. It will result in gametes with one chromosome less or one 
chromosome more, than normal. The progeny formed from such gametes 
are called polysomics. They will have fewer or more chromosomes than 
normal. 

In certain cases, whole set of homologous chromosomes do not 
separate in meiosis. It results in diploid gametes. Fusion of such gametes 
with a normal haploid gamete gives rise to progeny with a triploid 
chromosome number. This condition is called polyploidy. It is commonly 
observed in plants. Polyploids are usually more vigorous. Such forms can 
give rise to new species. 

While recombinations provide regular variations, mutations enrich such 
variations. Phenomena such as chromosomal abberrations, polysomics and 
polyploidy while, found advantageous to the organisms, provide new 
directions for speciation and further evolution. 

3. Recombination 

During meiosis, due to crossing over of chromosomes, genie 
arrangements get altered. Such alterations cause reshuffling of gene 
combinations. Such recombinations are regular events in gametogenesis. Due 
to such events new allelic formations happen and after fertilization variations 
result in the progeny. 

4. Hardy- Weinberg equilibrium (Population genetics) 

A population is defined as an assemblage of living beings showing a 
closely interacting system. A population comprising of sexually interbreeding 
organisms is termed as the genetic population or Mendelian population. 
A genetic population may be defined as "a community of similar individuals 
living within a limited circumscribed area at a given time and capable of 
interbreeding". The genes of all the individuals of such a Mendelian 
population will constitute the gene pool. A gene pool comprises a diverse 
forms of a gene combining and recombining by the process of sexual 
reproduction. The frequency of genes and genotypes in a population had 
been worked out by mathematical formulations. 



280 



The gene frequency refers to the proportion of an allele in the 
gene pool as compared with other alleles at the same locus. Hence the 
gene frequency can be calculated by substracting the number of a particu- 
lar gene in question from the total number of genes present on that locus in 
the population. 

If the frequency of gene 'A' is represented by 'P' and that of gene a 
by 'q' and at gene equilibrium condition their total frequency is represented 
by 1, then at equilibrium 

P+q= 1 
or p = 1-q 
or q = 1 -p 

A mathematical interpretation for the distribution of gene and 
genotype frequencies in the population was developed by R.A. Fisher 
(England) and Sewall Wright (United States) . A fundamental idea in the form 
of a law to understand population genetics was provided by G.H. Hardy of 
England and W.Weinberg of Germany in 1908. The law proposed by them is 
known as Hardy- Weinberg's law. It is the foundation of population genet- 
ics and of modern evolutionary theory. According to this law 'the relative 
frequencies of various kinds of genes in a large and randomly mating 
sexual population tend to remain constant from generation to genera- 
tion in the absence of mutation, selection and gene flow or migration. 

This law concerns a theoretical situation for a population not under- 
going any evolutionary change. Thus according to the law the normal 
mendelian genie frequencies are maintained under certain conditions only. If 
such conditions are not followed, the gene frequency will change leading to 
deviations and cause variations, such variation will be the sources for future 
evolution. 

5. Genetic drift or Sewal Wright effect. 

This theory was developed by Sewall Wright in 1930. It is concerned with 
the gene frequency of a reproducing small population. In a small population 
not all the alleles which are representatives of that species may be present. 
Thus the process of inheritance is in violation of Hardy-Weinberg law. In 



281 



such a small population a chance event may increase the frequency of a char- 
acter that has little adaptive value. Thus the genetic drift may remain a signifi- 
cant factor in the origin of new species on islands and other isolated popula- 
tions. Due to loss of alleles having low frequency, amount of genetic variation 
may get reduced in small populations. Further, continual mating within such 
populations may cause decrease in the proportion of heterozygotes and in- 
crease in the number of homozygotes. However the small population as a 
whole may develop characters different from that found in the main popula- 
tion. Such deviations may even lead to speciation or formation of a new 
species. 

When a small group of individuals due to genetic drift become founders 
of a new population the phenomenon is termed as 'founder principle' . The 
new population often has genotype frequencies different from the parent 
population. 

Sometimes genotypic frequencies may get changed in a small popu- 
lation isolated temporarily due to natural calamities. When the population 
regains its original size the members of the small population may have di- 
verged genetically from the original parental population. Hence interbreeding 
between members of small and larger populations may not be possible. The 
small population might have evolved into a new species. This type of genetic 
drift is referred to as bottleneck effect. 

6. Natural Selection :- 

In the modern or synthetic theory of evolution natural selection is 
considered as a population related genetic phenomenon. It leads to changes 
in allele frequencies and favours or promotes adaptation as a product of 
evolution. 

When the population size of animals or plants in specific locality 
increases certain environmental factors such as availability of food may 
become limiting factors. Those organisms exhibiting characteristics which give 
them a competitive advantage may survive. Thus population size and 
environmental limiting factor operate together to produce a selective 
pressure. The selection pressure may increase or decrease the spreading of 
an allele in a gene pool depending on its adaptive value. This inturn will lead 

to evolutionary changes. 

282 



There are three types of selection processes in operation. They are 
stabilizing, directional and disruptive selections. 

In stabilizing selection competition in nature is not severe. The 
phenotypic features coincide with normal environmental situations. 
However this selection may eliminate characters that are abnormal and 
harmful and it tends to maintain the phenotypic stability within population for 
successive generations. 

The directional selection operates in response to gradual changes 
in the environment. It operates within the phenotypic range available within 
the population. The selection gradually changes the phenotypic character 
towards a possible extreme condition found suitable for the changed envi- 
ronmental situation. This selection will increase the frequency of desirable 
phenotypic character within the population. Thus it results in gradual 
evolutionary change. 

In disruptive selection the selection pressure may favour the 
existence of more than one phenotype in a population. It may even split a 
population into two sub-populations. If gene flow between such sub-popu- 
lations is prevented a new species or a sub specie may evolve. When a 
disruptive selection produces more than one phenotype within a population 
the phenomenon is known as polymorphism. 

7. Polymorphism 

It is the "the existence in a natural population of two or more alleles 
in frequencies too large to be explained by recurrent mutation". 

Thus a polymorphic population will have several alleles of a gene as 
a permanent feature of the species. The varied alleles are favoured and 
maintained in the population by genetical mechanisms. 

A classical example for such a polymorphism could be the existence 
of a genetic disorder in humans, namely sickle-cell anaemia. This disease 
reduces the oxygen-carrying capacity of the blood and affects blood supply 
to various organs. This disorder is inherited as a Mendelian recessive. It is 
more frequent among American blacks than American whites. In spite of its 
harmful nature the allelic gene responsible for the disorder is maintained in 

283 



the black population. According to the work of Allison (1955, 61) it was 
shown that in Africa the same allelic gene conferred an advantage, that is it 
protected the inheritors of such gene from malaria. Thus the connection 
between sickle-cell anaemia and malaria was estabilished. Hence selection 
has encouraged the existence of such a polymorphic allele in the population. 

8. Isolating mechanisms 

A species may be defined as "a group of organisms that are 
reproductively isolated from other such groups". Thus the maintenance of a 
species as a dintinct group is due to several isolating mechanisms. They are 

1. Geographical isolation 

It is a common type of isolation. The isolation between populations is 
caused due to geographical barriers such as mountains, rivers, oceans, for- 
ests or deserts. These natural barriers prevent interbreeding between them. 
Thus mutations formed in one population will lead to the formation of new 
species. The existence of closely related species of frogs in Southern India 
and Srilanka is a classical example. These fresh water animals are prevented 
from interbreeding due to a narrow sea namely Gulf of Mannar. Because of 
isolation for a fairly long time they have evolved into distinct species. 

2. Premating isolations - such mechanisms prevent interspecific crosses. 

a) Ecological isolation - Members of the populations occur in different 
habitates in the same general region. 

b) Seasonal or Temporal isolation - Mating or flowering periods 
occur at different seasons. 

c) Sexual, Psychological or Ethological isolation - It is a behavioural 
isolation where males and females of the same species get attracted to 
each other. 

d) Mechanical isolation - Physical non-correspondence of the genitalia 
or floral parts. 

e) Gametic isolation - Spermatozoa, or pollen tubes of one species are 
not attracted to the eggs or ovules of another species. 

284 



3. Postmating or postzygotic isolations - These isolating mechanisms while 
allowing fertilization may prevent the hybrid zygote from further 
development. 

a) Hybrid inviability - The hybrid zyotes are inviable. 

b) Hybrid sterility - The hybrids develop but they remain sterile. They are 
incapable of producing a normal complement of functional sex cells. 

c) Hybrid breakdown - Fl hybrids are normal and fertile, but F2 contains 
many weak or sterile individuals. 

Speciation :- 

A species is a natural, biological unit. Among the various taxa, a 
species is not man made. It is a natural reality. The process of evolution 
operates at the species level only. It is because of these reasons, in evolution 
much importance is given to the 'Origin of Species' . There are several types 
of species. 

Allopatric species - Species occupying different geographical areas. 
Ex : species of frogs in India and Srilanka. The two land areas are separated 
by the Gulf of Mannar. Sympatric species - closely related species living 
together in one common locality, yet maintain their species identity Ex: Rana 
hexadactyla, R.tigrina and R.cyanophlictis living together in a pond. 



285 



8. AQUACULTURE 

Resources from fresh water and marine systems are being exploited by 
human beings mainly for food. The rate of exploitation is so high that the natural 
cycle is getting disturbed .The quantity offish caught is much higher than the egg 
laying capacity of the fish. Further, by man made interferences like pollution, 
enhanced rate of infection, depletion of water bodies , etc . , the fish population is 
adversely affected. With the present rate of exploitation, the once infinite fish 
food resource, is now becoming finite. Aquaculture is a methodology which is an 
alternate remedy for the above situation 

Aquaculture is a branch of science that deals with the farming 
of economically important aquatic organisms and plants, under 
controlled and in a confined environment. 

Brief history : Aquaculture is an ancient culture technique. It was first 
practiced in Asia. Chinese, in 3500 BC raised carps in ponds. They also 
developed breeding techniques for increased production. Today China 
dominates in Aquaculture industry. Currently Aquaculture practices all over 
the world are growing as fast as any other type of agriculture. Aquaculture in 
India is one hundred years old. Till the end of 19 th century the method of 
pond management was mainly confined to West Bengal, Bihar and Orissa. 
Later, it gradually spread to other states including Tamilnadu. 

Prospects of Aquaculture : 

1. There is an increasing global demand for food. It is predicted that in 
another fifteen years animal proteins alone will provide 40% of the world's 
need. 

2. As the growing population needs more food, increased aquaculture 
production would reduce the pressure on natural population. 

3. Aquaculture helps to promote economic development in rural and 
under developed areas. 

4. Culture of selected varieties offish will help in good yield of commercial 
forms 

286 



5. The desirable fish being cultured in pond makes the process of harvesting 
easy and economical. 

6. Fishes are healthy sources for animal proteins and are easy to digest and 
such an animal protein can be harvested on demand. 

Major kinds ofaquaculture: 

The Aquaculture can be broadly classified into freshwater culture, 
mariculture, brackish water culture and metahaline culture. This 
classification has been made according to the variations in salinity of the 
respective culturing system. 

Fresh water Aquaculture : Water is considered to be 'fresh water' when 
the salinity is < 0.5%o (parts per thousand or ppt). Culturing of 
organisms in this water is known as fresh water aquaculture. Fresh water 
aquaculture includes earthen pond culture, temple tanks culture, 
irrigation tanks culture, race way culture; sewage- fed fish culture, 
re-circulatory system culture, ornamental fish culture, larvivorous fish 
culture, food organisms culture sport-fish culture and integrated fish 
culture. 



FRESHWATER 
CULTURE (<0.5%c) 









barthen ponds 


> 




V 


1 


Temple-tanks 


Composite fish 



Irrigation tanks 



Mono sex 



Raceways 



Mono species 



Paddy - 


Fish 


A 


Banana 


- Fish 


i«. 


Duck- 


Fish 


A 


Poultry 


- Fish 


A 


Pig - Fish 


A 


Cattle - 


Fish 


A. 



Sewage ponds 



Air breathing fish 



Recirculation system Murrel - tilapia 



Ornamental fish 



Larvivorous fish 



Food organisms 



Sport fish 



Integrated 
287 



Fig. 8.1. Different fresh 
water aquaculture practices 



Earthern pond culture : An excavated terrain enclosing a small shallow body 
of water is termed pond. Culture of fish in this pond is known as earthen pond 
culture. Earthen pond fish culture comprises monosex culture, monospecies 
culture, composite fish culture, air-breathing fish culture, predator-prey 
culture. 

Monosex culture: In this practice male and female fishes of individual 
species are cultured separately to enhance growth and yield. 

Mono species culture: It is a culture of only one species offish in a pond. 

Air breathing fish culture: Air breathing fish species such as Channa 
marulius, Channa striatus are cultured in this practice. These fishes can 
utilize the poor oxygen content of the shallow water due to the presence of 
accessory respiratory organ in addition to gills. 

Predator-prey culture (Murrel - Tilapia culture) 

The carnivorous fishes like murrels are cultured along with their prey 
fishes like Tilapia. This can be undertaken even in shallow and swampy ar- 
eas. 

Composite fish culture : Culture of different species of fishes together is 
called composite fish culture. It is also known as polyculture. The objective 
of this type offish culture is to select and grow fishes of different feeding 
habits in order to exploit all types of food available in different regions of 
pond. In this type offish culture, fast growing fishes namely Indian major 
carp, rohu, mrigal, silver carp, common carp and grass carp are usually 



cultured. 



Grass carp 



phytoplankton 




zooplankton 

Catla 
Silver carp 



Rohu 
Mrigal 



Fig.8.2. Composite fish culture 

288 



Fish culture in temple tanks: Fishes like tilapia, common carp, murrel 
and catfish are being cultured in temple tanks. 

Fish culture in irrigation tanks: The fishes such as Indian major carps 
exotic carps (brought from other countries) are profitably grown under this 
system. These tanks are provided with inlet and outlet facilities for the entry 
and exit of water. 

Race way culture: In running water systems like streams, a series of 
rectangular or circular earthen or cement tanks are constructed for fish 
culture.lt is used for carp fish culture. 



outlet 



fish pond 




Fig.8.3. Raceway 

Sewage-fed fish culture: Sewage is the liquid waste discharged from 
domestic and industrial sources within an area.lt is reutilized for culture of 
fishes like rohu, mrigal and catla. 

sewage and waste ~ j_ 



effluent 



waste stabilisation pond 




■ to irrigation 



water dilution 



over-flow 



Fig.8.4. Fish pond utilising sewage. 

289 



City sewage is extensively used for fish culture in Calcutta. Before 
sewage is let in to a pond , it is diluted with the fresh water so as to maintain 
the dissolved oxygen content and reduce other toxic substances 

Culture in water re -circulation system: 

This method can be adopted, where water scarcity prevails. Fishes 
are cultured in tanks where water is circulated continuously through tap. 

Ornamental fish culture : As a flourishing business and for hobby, aquarium 
fishes such as guppy, molly, gourami, sword tail etc. are cultured in aquarium 
tanks. 

Larvivorous fish culture : It is the culture of the mosquito 
larvae- controlling fishes such as tilapia, gambusia etc. As these fishes are 
controlling the vectors, human population can be saved from many diseases. 

Culture of fish- food organisms : As the mass culture of protein rich live 
fish-food organisms namely cladocerans, rotifers and tubifex worms have 
been found to be essential for growing larvae of fish, they are cultured in this 
system. 

Sport fish culture: Cold water fish such as salmon and trout which are 
mainly of sport value are cultured in places of high altitude like Kashmir, 
Himachal Pradesh, Ootacamund and Kodaikanal. The water bodies of the 
hills are characterized by the low temperature. 

Integrated fish culture: Culture offish along with agricultural crops such 
as paddy, banana and coconut and livestock such as poultry, duck, cattle 
and pigs is known as integrated fish farming. 

Fish farming with agricultural crops: Fish culture in paddy field is 
carried out in two ways namely simultaneous culture and rotation 

culture. In the former, rice and fish are cultivated together and in the latter, 
fish and rice are cultivated alternatively. The species of Catla catla and 
Anabas testudineus are cultured in this practice. 

When banana or coconut is cultivated in rows of wetlands, the ditches 
made between such rows are used for fish culture practice. This culture 
system is made successful due to continuous supply of water. Larvivorus 

290 



air-breathing fish species such as Channa marulius, Channa striatus and 
Tilapia mosambica species are cultured in this system. 




Fig.8.5. Flow chart showing various aspects of integrated farming 



Fishfarming with Livestock : In this practice, excreta of ducks, chicks, 
pigs and cattle are either recycled for use by fish or serve as direct food for 
fish. 

Duck-fish culture : Ducks are known as living manuring machines. The 
duck dropping consists of inorganic substances and therefore it acts as a 
source of fertilizer in fish pond. Besides, the ducks feed on unwanted 
insects, snails and their larvae which may be vectors offish pathogenic 
organisms. Fish of more than 10cm size alone should be cultured along with 
duck, otherwise the duck may feed on the fingerlings. Silver carp, catla, and 
common carp are ideal for duck-fish culture. 

Chicken-fish culture : The droppings of chickens, rich with nitrogen and 
phosphorous, would enhance the fertility of the pond. Poultry housing 

291 



constructed above the water level using bamboo poles would manure the 
pond directly. The giant fresh water prawn Macrobrachium rosenbergii, 

silver carp, tilapia, common carp, murrels are cultured in this practice. 

Cattle- fish culture : For this culture cow sheds and bio-gas plants are 
constructed near the fish pond. The slurry from the bio-gas plant may be 
discharged into the fish pond to enhance the nutrients of culture system. 

Pond culture : Knowledge of the construction of different types of fish 
ponds is essential for a profitable fish culture. The pond may be a artificially 
constructed one or a natural mass of water turned in to a pond. The essential 
feature of the pond is that it must be manageable for controlled farming. 

Structure of a typical pond : A typical earthen pond comprises the 
following structures such as bunds, harvesting pit, inlet and outlet. 

Bunds 

Bunds are the protective structure of the pond. Bunds are of three 
types, namely (i) main or peripheral bunds, (ii) bunds holding water on one 
side, (iii) bunds dividing two adjacent ponds. The longevity of any bund 
depends on quality of soil, slope and crown or crest. 

A bund has a crown or crest and a slope. Bunds in clay soil are 
steeper than sandy soil. The crown must be a minimum of 1 meter width. If 
the production pond is more than 0.5 hectare, a platform like space between 
bund and water area should be made available. This area is known as berm 
or bench line. 

For construction of bund, sandy or gravelly soil is not suitable 
because it may produce fracture (cleaves) in the bund and cause seepage. 
Hence a mixture of silt, sand and clay in the ratio of 1 :3:2 is more suitable for 
the construction of bund. 

Harvesting pit : The pond which is used to capture the cultured fish after 
attaining maturity is called harvesting pit. The bottom of the harvesting pit 
before being filled up with water, should be levelled and cleaned of debris, 
stones etc. A slight slope from one end to the other end in the case of 
undrainable fish pond may be provided at the bottom. 

292 



Inlet and outlet : Fish ponds are provided with inlets and outlets to 
facilitate smooth filling and de watering. The inlet and outlet should be 
devised in such a way that it prevents the entry of wild fish inside and 
escaping of culture fishes. The pipe size of the inlet and outlet will vary 
according to the size of the pond. The outlets are usually set at the lowest 
area of the pond. 

Types of ponds : Ponds can be classified on the basis of their utilization, as 
hatching pit nursery ponds, rearing ponds and stocking ponds. 

Hatching pit : These are small tanks usually measuring (2.5 x 1.5 x 0.5m). 
They are used for hatching fertilized eggs. They are located near the riverine 
collection grounds. The hatching pit must have facility for continuous and 
slow flow of water. It also must be provided with an enclosure of fine mesh net 
called Hapa .The hapa is rectangular in shape. It is held on four bamboo poles, 
one at each corner. The size of hapa and mesh of its net differ according to use 
.This hapa prevents the escape of the laid eggs and protect the eggs from the 
predators. 




Fig.8.6. Hapa 

Nursery ponds : It is a seasonal pond having the dimension of 12 x 6 x 1 m. 
It is mainly used to nurse the hatchlings for a period of three weeks until they 
become fry. The fry is a recently hatched tiny fish less than 2.5 cm in total 
length. The maximum permissible density of hatchlings is about 10 millions/ha. 



293 



Rearing ponds : These ponds may be seasonal or perennial and used for 
rearing advanced fry for 2-3 months. It is fairly larger than the nursery pond 
and has the size of 25x12x1 m. Here the fry is grown for about 2 months until 
they reach fingerling stage. Young ones of a fish having more than 2.5 cm to 
10cm in total length is known as fingerlings. 

Stocking ponds : These are larger than nursery and rearing ponds. The size 
of the stocking pond should be 0. 1 to 2.0 ha. The fingerlings are stocked and 
grown in this pond until they attain marketable size. 

Location of a fish pond 

There are three important factors to be taken into consideration to 
choose a good site for a fish pond. They are (i) Topography (ii) Soil type 
(iii) Water source. 

Topography : The term topography means the surface features of the area. 
The ideal topography of a fish farm site is a gently slopping terrain of a wild 
valley. The fish farm site may also be bowl shaped area with highlands on 
three sides, and a narrow outlet on the fourth side. 

Soil type : Second important part of site selection is the soil of the area. The 
soil of the pond must be able to hold water. A pond containing lot of clay will 
be ideal for retentivity of water in it. 

Water source : The dependable sources of water for pond are from, (i) lake 
and reservoirs (ii) springs (iii) rivers (iv) streams (v) canals (vi) surface runoff 
and (vii) wells. While supplying water to the ponds, water should be filtered 
carefully. 

Physico-chemical and biological factors for pond fish culture 

The important physico-chemical factors affecting fish culture are water 
depth, temperature, turbidity and incident light, oxygen, p H , carbon-di-oxide 
and hardness of water. 

Physical factors 

Depth : In a shallow pond, sunlight penetrates up to the bottom and 
increases the productivity by photosynthesis. If the pond is too shallow, 

294 



water gets heated up during summer and affects the survival offish. Hence, 
two meters deep ponds are ideal for maximum productivity. 

Temperature : The suitable temperature for different fishes varies from 10°C 
to 37°C. For example Tilapias can not survive at 8 C, Indian major carp 
cannot survive below 16 C and tropical fish cannot survive around 
10°C-12°Corless. 

Turbidity : Water becomes turbid due to suspended matter like silt and 
clay. Turbidity affects respiration of the fish, since the gills get chocked due 
to deposition of suspended matter. Therefore water should be free from 
turbidity. 

Light : In shallow ponds light reaches up to bottom and influences heavy 
growth of vegetation. Incidence of light is also responsible for the production 
of plankton. The light controls photosynthetic activity of plants, thus 
indirectly affecting flora and oxygen content of the pond. 

Chemical factors : Productivity of a pond depends on the presence of the 
following chemical factors. 

Oxygen: The oxygen requirement for cultivable fish varies from species to 
species. If there is low concentration of oxygen, fish migrate to surface or 
crowd near inlet. In extreme depletion of dissolved oxygen level, fish may 
die of asphyxia. 

TT TJ 

p ; Ideal p range for pond water is 6.5 to 9.0. Sudden fluctuations in P H 
are always harmful. In general neutral or slightly alkaline water is more 
productive than acid water. 

Carbon-di-oxide : Though presence of carbon-di-oxide is essential for 
photosynthesis, excess of dissolved carbon-di-oxide is harmful to fish 

Hardness of water : Hardness depends on the amount of calcium and 
magnesium salts dissolved in water. The suitable hardness for the growth of 
fish in pond water is 15ppm or above. Less than 5ppm cause slow growth 
and eventual death offish . 

295 



Biological conditions of pond water : The productivity of a pond 
depends upon a large number of animals and plants living in various zones of 
the pond. The important aquatic plants are vallisneria, hydrilla, 
chlorella, and the floating plants are eichornia, pistia, salvinia, lemna 
etc. For a good fish culture practice, along with aquatic plants the growth of 
right type of plankton is also essential. 

Maintenance of pond 

The productivity of the pond is enhanced by a) controlling the 
vegetation, b) cleaning the bottom, c) liming and d) manuring . 

All undesirable plants and weeds must be removed regularly. The pond 
should be emptied, dried and cleaned at regular intervals to avoid the silting of 
pond. The application of quick lime raises the P H of water and kills the bacteria 
and other fish parasites .Quick lime is generally spread on the pond bottom 
before 10-15 days of stocking the pond with fish. Liming is done every year 
regularly. Introduction of inorganic nitrogenous and organic fertilizers increase 
the growth of phytoplankton, zooplankton and filamentous algae which are the 
natural food substances of growing fishes. 

Cultivable fresh water fishes : (i) Catla catla (ii) Labeo rohita(Rohu) 
(iii) Labeo calbasu (iv) Labeo bata. (v) Cirrhina mrigala (vi) Cyprinus 
carpio (vii) Clarius batrachus (viii) Tilapia mossambica (ix) Osphronemus 
gouramy (x)Anabas testudineus and (xi) Channa striatus are some of the 
fresh water cultivable fishes. 

Macro brae Mum rosenbergii (giant river prawn) M.Malcolmsonii 
(monsoon river prawn) M. idae (river prawn) are some of the fresh water 
cultivable prawns. 

Bionomics of cultivable fishes 

Catla catla (Indian major carp) : It is characterized by a deep body with 
conspicuous head; mouth is large and upturned; there are no barbels; lips are 
non-fringed, spawning takes place after sudden heavy rain fall. It feeds on 
zooplankton and grows to a maximum size of 1 .8 meters weighing 45kg. It is 
widely distributed in Pakistan, Bangladesh and India. 



296 




Fig.8.7. Cattla cattla 

Labeo rohita (Rohu) : It is popularly known as 'rohu ' . It is considered as a 
palatable fish; it has a small and pointed head ; mouth is terminal with fringed 
lower lip; body colour is brownish grey or bluish on the back; fins have pink 
colour; it feeds on plankton, detritus and mud; body attains a total length of 1 
meter weighing 900gms. Breeding and distributions are similar to that of Catla. 




Fig.8.8. Labeo rohita 



Tilapia mosambica 



It is an exotic fish brought from Africa. The colour of the body is 
brownish or blackish; mouth is large as wide as head; it is a fast growing hardy 
fish. ; it does not survive below 1 0°C ; it can also be cultured in rice fields and in 

297 




Fig.8.9. Tilapia mosambica 



sewage water ponds; it breeds throughout the year; the adult is chiefly 
omnivorous; it grows to a length of about 35 cm. and female tilapia exhibits 
buccal incubation. 

Bionomics of freshwater prawn 

Macrobrachium rosenbergii: Besides the culture offish, freshwater prawns 
are also being cultured throughout the world. 




Fig.8.10. Macrobrachium rosen bergii 



Though about 150 species of fresh water prawn are found 
distributed all over the world, only 40 species of genus macrobrachium are 
found distributed in the rivers, reservoirs and estuaries of India. Among the 

298 



common species of macrobrachium the giant fresh water prawn, 
macrobrachium rosenbergii grows faster and it tolerates wide range of 
temperature and salinity changes. Moreover, it has less cannibalistic tendency. 
Because of these reasons, it is found to be most suitable for culture. It is 
cultured in large scale by countries like Hawaii, Mauritius, Taiwan, Thailand, 
Philippines, Malaysia and Indonesia. 

Salient feature and distribution: It grows to a maximum size of 320 mm 
weighing 200 gms. Matured males are not only larger than females but also 
possess enlarged second pair of waking legs. The juveniles can be identified 
by 1-8 horizontal line on the carapace. This species is distributed from lower 
to upper surface of the river. It prefers shallow and muddy environment. 

Breeding of Macrobrachium rosenbergii : Breeding takes place 
throughout the year. The peak of the breeding season is found to be during 
March to May on the east coast. Similarly on the west coast, the peak breeding 
activity occurs during October to November; the fecundity of a female may 
be 10,000 to 50,000 eggs. Fecundity can be defined as the number of ova 
that are likely to be laid by a fish during the breeding season. 

The larvae feed mainly on zooplankton. Adult prawns feed on aquatic 
insects, algae, molluscs, crustaceans, etc. In the absence of the natural food, 
these animals become cannibals. 

Induced breeding in fish culture 

The practice involved in prompting the fish to breed in confined water is 
known as induced breeding . Induced breeding technique enhances seed 
productions. It is performed by a technique called hypophystation. The 
hypophy station is a process of stimulating the breeding activity offish through the 
injection of pituitary extract resulting timely release of eggs and sperms from the 
ripe gonads. The extract should come from the healthy pituitary gland of healthy 
fish of the same species or closely related one. 

Induced breeding technique 

This technique involves (i) preparation of pituitary extract 
(ii) selection of breeder (iii) injection to breeder (iv) spawning in breeding 
hapa. 

299 



(i) Preparation of pituitary extract : For the preparation of extract, the 
pituitary gland is removed by dissecting the head from gravid donor fish. The 
removed pituitary glands are kept in absolute alcohol for dehydration. Then 
the glands are preserved in fresh alcohol contained in dark coloured pvals 
and stored in a refrigerator. The preserved pituitary glands are then softened 
in an instrument called homogenizer with distilled water. The extract 
prepared by centrifugation method is stored in vials 

(ii) Selection of Breeder : The breeder to be selected must be healthy, 
fully ripe and of medium size. The preferable age group may be ranging from 
two to four years and weight may be ranging from 1 to 5 kg. 

(Hi) Injection to breeder : Intramuscular injection of pituitary extract is 
administered with a hypodermic syringe. In usual practice, female alone is 
administered with a stimulating dose of 2 to 3mg/kg weight. After 6 hours a 
second dose of extract with 5 to 8 mg/kg is also injected. Similarly males are 
also injected with the first dose of 2-3 mg/kg of body weight of the recipient 
fish. 

(iv) Spawning in breeding hapa : The injected male and female breeders 
are kept together in a rectangular enclosure called 'Hapa' . The hapa is made 
of mosquito net cloth to prevent breeders from escaping. The release of 
matured eggs and sperms called spawning, takes place after 3-6 hours. 

Nutrition for culture fish : Knowledge about nutrition would help the fish 
culture practice to remain more lucrative. The nutritional requirements such 
as protein, amino acids, fats, carbohydrates, vitamins A,D,E & K. must be 
the constituents of their food material for enhancing faster growth. 

Fish diseases : Like all other animals, fishes are also liable to be attacked 
by viruses, bacteria, fungi and different parasites and get diseased. 

Viral hemorrhagic septicaemia(VHS) 

The symptoms of this disease are general anemia, discolouration of 
gills, swellings of eyes, Oedema of muscles. It is caused by virus. 

Sapro legniasis 

This disease is caused by a fungus. It is a very common water mould 

300 



disease. Ulceration or exfoliation of skin, blindness and hemorrhage are 
certain symptoms of this disease. 

Gill rot 

It is another fungus disease. Appearance of small red spots on gill 
filament is the symptom of this disease. This leads to suffocation and 
ultimate death. 

Dropsy: It is caused by a bacterium. The symptoms of this disease are 
accumulation of water fluid in the body cavity, inflation of intestine and 
protrusion of scales and eyes. 

Costiasis : It is caused by a protozoan parasite. Bluish mucous coating on 
the skin, fin and gills are the symptoms of this disease. 

Control of the fish parasites 

Various fish diseases caused by external parasites are removed and killed 
by the use of certain chemicals such as copper sulphate , potassium 
permanganate, acetic acid , formalin and common salt etc. The simplest 
treatment for the affected fresh-water fish would be their transference to sea 
water and vice versa. The affected fish are dipped or bathed in a tub containing 
solution of the chemical for a required length of time and then the fish is replaced 
in freshwater. 

Ornamental fish culture 

Ornamental fishes have attractive colouration, peaceful nature, tiny 
sizes. They are suitable for keeping in captivity. They have adaptability for 
living in confined spaces. Therefore these fishes are cultured for hobbies and 
commercial purposes in glass tanks. Establishment of glass tanks in which 
living colourful ornamental fish and plants are kept for exhibition, is known 
as aquarium. The aquarium had its origin in Japan and China. About 600 
species of ornamental fishes are grown for hobby and export. 

Setting up of an Aquarium tank : Aquarium tanks are made with glass 
sides and bottom. The glass plates are fixed by red lac or aquarium cement. 
The tanks are mostly rectangular in shape. Shallow and wide tanks are 
preferable for aquarium. The surface water of tank should have oxygenation 

301 



through atmospheric contact. The ideal size of aquarium tank may be 
60 x 30 x 30cm or 90 x 30 x 40cm. It is also essential to have a cover with 
provision for installing lights and feeding. The tanks are cleaned with tap 
water. The aquarium tank may be placed on a table near a window so that it 
receives sufficient light. If the natural light is not adequate, artificial light by 
means of bulbs or fluorescent tube may be provided. 







ji-.^-fe 




"••■•■• • 



■•-•'■'-•— 



Fig.8.11. Aquarium tank 

Small stones and fine gravels are selected for spreading at the 
bottom of the tank along with coarse river sand. The bed must be porous. 
Aeration may be done by providing a small piston or diaphragm type 
aerator. The air bubbles of aerator will drive away the carbon-di-oxide 
accumulated at the bottom water. 

Water quality of Aquarium tank : Pure rain water or tap water without 
chlorine content may be ideal for aquarium tank. Water should be devoid of 
hardness. For reducing hardness of water, water is mixed up with soft water 
such as rain water. 

Planting : Plants such as vallisneria and myriophyllum are planted in the 
tank. They not only give shelter and shade, but also utilize the carbon-di- 
oxide released by the fish and liberate oxygen for fish through 
photosynthesis. 

Fresh water ornamental fishes 

Guppy :- These are small coloured fishes (3cm). It is an exotic variety 
originating form central America. The colours may differ greatly. Males are 

302 



^-*-^(&s Fig.8.12. Veil tail guppy 

irregularly marked in red, orange, green or black. Females are larger than 
males. Males have enlarged, coloured caudal fins. The female stores sperms 
inside the body and give birth to young ones (Live bearers). These are 
omnivorous fishes occupying all levels in an aquarium tank. These are peaceful 
fishes. There are several varieties of guppies. They are gold cobra, uncoloured 
red tailed half black, blond and red varitail. 

Sword tail : These fishes have a coloured stripe along the side, and a yellow 
sword like caudal fin extension. The edges of 'sword' are black. There are 
several colour variance. The females are normally without a swordtail. The 
male fishes may quarrel among themselves. These are omnivorous fishes. 
They occupy all tank levels. The varieties are gold sword tail, pine apple 
sword tail, red wag, lyre, black calico sword tail. 




Fig.8.13. Sword tail 

303 



Platy : The most common platy is the wag tail. It is a very popular variety 
with a black mouth and black fins and red or yellow body colours. These are 
omnivorous fishes living in all tank level. 




Fig.8.14. Platy 

Gourami : These are oval shaped fishes. They have conspicuous dark ver- 
tical bars on lateral sides. They have an upturned mouth. The pelvic fins are 
filamentous. These are peaceful, herbivorous fishes. They can be reared with 
other larger fishes. The varieties of gourami are giant gourami, thick lipped 
gourami , dwarf gourami, kissing gourami, pearl gourami etc. 




Fig.8.15. Gourami 



304 



Siamese fighting fish: These fishes are adapted to live in oxygen depleted 
water. These are native to Thailand. The males have long flowing fins. Colour 
and fin development differ greatly. Males are aggressive. Hence, it is 
advisable to keep only one per tank. 




Fig.8.16. Siamese fighting fish 



Angel fish: These fishes have laterally compressed disc like body. They 
have long trailing fins. They are popular because of the elegant outlines and 
graceful swimming movements. They exhibit parental care. 




Fig.8.17. Angel fish 

Discus fish: The body is round and laterally compressed. It resembles a 
disc. Dorsal and anal fins are long based. These fishes need high quality 
water and separate aquarium tank. These are carnivorous fishes occupying 
middle and lower level of the tank. 

305 









Fig.8.18. Discus fish 

Pencil fish: These are pencil shaped fishes. The dorsal surface is golden 
brown and underside is silver in colour. A golden band runs on the lateral 
sides. These are omnivorous fishes commonly living in the middle level in 
tank. The varieties are golden pencil fish, red pencil fish, and three lined 
pencil fish or one lined pencil fish. 




Fig.8.19. Pencil fish 



Gold fish: These were the earliest domesticated ornamental fishes. 
Commonly the body colour is metallic red-orange. Dorsal and anal fins are 
relatively long based and the caudal fin is forked. These are omnivorous 
fishes occupying middle and lower level in the tank. 

306 




Fig.8.20. Gold fish 



These fishes were developed in 11 th century in China. Through 
selective feeding Chinese have developed several varieties of gold fishes such 
as comet, nymph, shubunkin bubble-eye, fan tail, lion head moor, pom-pom, 
vailtail etc. 

Koifish : These are suited for outdoor aquaria. It is customary to view 
these fishes from above. Accordingly colour patterns have been developed. 
The adults are torpedo-shaped. The varieties include shiro-bekko, kohaku, 
taisho sanke etc. 







* w P — *# < ■*-"" 



Fig.8.21. Koi fish 



Other common ornamental fishes include barbs, danio, rasbora, shark, 
tetra, hatchet fish etc. 

Feeding 

Sword tails, Kissing gourami and mollies feed on algae which grow 
around the stones and in water sources. Live protein-rich foods such as 

307 



Cyclops, tubifex worms, mosquito larvae etc. are considered as excellent 
food sources. Fresh foods such as chopped earthworm, fish paste, scraped 
boiled fish are also deemed to be good items. Artificial pelleted fish feeds 
can also be given to the aquarium fishes. It is always better to feed the aquarium 
fish with different kinds of foods. As far as the feedings is concerned, 'feed 
little but often' is the best method. Fish may be fed once or twice a day. 
Excess food and detritus may be removed 30 minutes after feeding by 
siphoning out with rubber tubing. 

Mariculture 

The term mariculture refers to culture of marine organism in pollution 
free marine water. Generally, the mariculture practice is done at the edge of 
oceans inshore area. The optimum salinity range of mariculture is 30 - 35%o. 
The mariculture includes (i) floating culture (ii) raft culture (iii) racks culture 
(iv) pole culture (v) long line culture (vi) on-bottom culture (vii) coir rope net 
culture or nylon rope net culture 



MARICULTURE 

(30% o -35% o 




V 






Floating cage 






V 






Rafts 






V 






Racks 






V 






Poles 






V 






Longline 






V 






On - bottom 












Coir or nylon rope net 





Floating cage : Cages are made of steel wire frame with nylon meshes. 
The split bamboo mats are also used as frames. The cages are left floating by 
means of strong floats. The fishes such as carps, cat fishes, anabas, tilapia 
are cultured in this method. 



308 




Fig.8.22. Floating cage 

Raft culture : Rafts are usually constructed with casuarina or eucalyptus 
poles of chosen length. A raft of the size 6m x 5m is found to be suitable one. 
By this method oysters are cultured. The seeds of the oysters called 'spat' 
stick on to the rafts and grows up to its maturity. 



^m 



^ 




spat 



J&L 



Rack culture : This culture method is possible only in shallow and calm sea 
of 2-4 meter depth. It is a fixed structure made of stake or eucalyptus poles. 
Cross and horizontal poles are arranged on the top of the poles and lashed 
with coir rope. The racks thus constructed remain always above the water. 
The overall size of the rack is lOmxlOm. Oysters are cultured by using racks. 

309 



Pole culture :Wooden poles are placed upright in the inter tidal zone. In 
this method, ropes with spat attached are wound around large vertical poles 
called bouchots. Mussels and oysters are cultured by this practice. 




oyster 



wooden pole 



Fig.8.24. Pole culture 
Long line culture : In this method about 60m rope is stretched horizontally 
near the water surface. This rope is anchored at both the ends with concrete 
blocks. Series of floats are fixed at 3m intervals on the rope. Vertical lines of 
6m length seeded with mussel spats are hung between two floats in the main 

line. Mussels are being cultured by this method. 

.. „ . . ymain long rope 

l_ \_ J) _T 2 _ ( )/ ( "") ^V " ^ synthetic float 

FT 




stone 



anchor cable 



anchor 



Fig.8.25. Long line culture 



On -bottom cultivation : In on- bottom cultivation mussels are collected 
from the area of its abundance and then they are spread out at the area 
where lower density of the mussels occur. 

Coir or nylon rope net culture : Coir or nylon ropes are fabricated in the 
form of nets and these nets are tied on fixed poles. Seaweeds are cultured by 
this technique. 

310 



Some of the cultivable species in marine aquaculture: 

Sea weed : (i) Porphyra texara, (ii) Gracilaria edulis. 

Edible oyster : (i) Ostrea edulis, (ii) Crossostrea madrasensis. 

Pearl oyster : (i) Pinctada fucata, (ii) P.margaritifera. 

Mussels : (i) Mytilus edulis, (ii) Perna viridis 

Prawn : (i)Penaeus indicus, (ii) Pmonodon. 

Crab : (i) Scylla serrata. 

Fishes : (i) Chanos chanos, (ii) Mugil cephalus. 

Lobster : (i) Panulirus polyphagus, (ii) Phomarus 

Edible oyster 

Crossostrea madrasensis is the common edible oyster of India. It 
releases about 10-15 million eggs. It is cultured by rack and tray method. 
The water should have salinity range of 10-32%o. Water must be free from 
industrial and sewage pollution. The spat of edible oysters are allowed to 
grow to a larger size and kept in trays. These trays are placed immersed on 
the racks. Oysters of marketable size of about 90 mm length are obtained. 




Fig.8.26. Edible oyster 

Oyster meat is nutritious and it consists of 52% protein, 14% 
glycogen and 11% fat. Oyster powder contains wide range of minerals, 
vitamins and amino acids. It has been found to be good for skin care, 
numerous heart ailments, blood pressure, liver problem, arthritis and 
rheumatism. 

311 



Pearl oyster 

The most important among the pearl producing species are Pinctada 
fucata and P.margaritifera. In India cultured pearls were produced for the 
first time in 1973 at Tuticorin. They are sedentary animals. Pearl oysters are 
found along the coast of Capecomorin and in the Gulf of Kutch. 





Fig.8.27. Pearl oyster 

Fig.8.28. Pearls 

Pearl oysters are farmed by racks, raft, and long line methods. The 
rack method of culture can be done where there is a depth up to 2.5 m. The 
remaining two methods are employed where there is 8 m and 15m depth 
respectively. Optimum salinity range for pearl oyster culture is 30%o.Since 
pearls are utilized for ornamental purposes, its culture is also a commercially 
important one. 

Seaweed culture 

Seaweeds are marine algae. They are non-flowering plants without true 
roots, stem and leaves. Seaweeds occur on rocks, dead corals, stones, pebbles, 
solid substrata and on other plants. They grow abundantly in south coast of 
Tamilnadu, Gujarat coast, Lakshadweep and Andaman-Nicobar islands. There 
are also rich seaweed beds around Mumbai, Ratnagiri ,Goa , Chinna Muttam, 
Idinthakarai, Uvari, Mandapam, Kovalam and Pulicat in Tamilnadu. 

Being rich with minerals, vitamins, trace elements and bioactive 
substances seaweeds are called medicinal food of 2 1 st century. As they are widely 
employed in many industries like food, confectionary, pharmaceutical, dairy, 
textiles, paper and paint, currently most of the countries have involved in 

312 




Fig.8.29. Seaweeds 

seaweed culture practice. Large -scale seaweed culture is carried out only in 
Asia. China holds first rank in seaweed production. Seaweed has been a staple 
food in Japan and China for a very long time. 

Some of the commercially important seaweeds cultured in Indian waters 
are, Gracillaria (red algae), Porphyra (red algae), Laminaria (brown algae) and 
Enteromorpha (Green algae). 

Seaweeds are cultured by rope net made of coir or nylon and by long 
line rope methods. The fragments of the seed (plant) material are directly 
inserted in to the twists of the coir ropes . The seed- twisted coir or nylon ropes 
are fabricated in the form of nets and later they are tied to wooden poles fixed in 
the coastal waters. The seaweeds are then harvested after a period of 25- 60 
days. 

Marine ornamental fishes 

The marine ornamental fishes are inhabitants of coral and rocky 
areas of marine environment. They are abundant in Gulf of Mannar , Palk 
Bay and Gulf of Kutch in the mainland coast and in the Lakshwadeep and 
Andaman islands. In Lakshadweep Islands more than 300 species of 
attractive colours and shapes are available . Damsel fish, cardinal fish, 
groupers, unicorn fishes, butterfly fish, goat fish, gobies, squirrel fish, trigger 
fish, scorpion fish are available in Lakshadweep Islands . In Andaman group 
of Islands about 150 species of ornamental fishes are known to be available. 
Sat fish, bok fish, trigger fish, coral fish and spine foot are some species of 
this region. Gulf of Mannar and Palk Bay have several islands with extensive 

313 




Angel fish 



Regal angel fish 





Scorpion fish W 



Butterfly fish 





Grouper 




Scat fish 



Fig.8.30. Ornamental fishes 

coral reefs around them. About 100 species of ornamental fishes are found 
in this region. 

Brackish water culture 

Brackish water is water that is saltier than fresh water, but not as 
salty as sea water .The culture of aquatic organisms in saline water having 
salinity range >0.5 - 30%o is known as brackish water culture. In brackish 
water areas, milk fish, sea bass, mullet, mugil species and prawns are 
cultured by installing bamboo or nylon enclosures. These enclosures are called 
pens. In brackish water, mussels and oysters are also cultured by pole, rack, 
raft and rope culture methods. 

314 



Sea bass: {hates calcarifer) 

The very prominent fish culture in brackish water is sea bass, which 
is also known as giant perch or cock-up. The popular name for seabass is 
"koduva" in Tamilnadu. It is a fast growing carnivorous fish. It attains 
average size of 1 .0 -1 .2 kg in a year. Though sexes are separate , seabass is 
a protandrous hermaphrodite. Males are generally small and convert into 
females as they reach size above 5.0 kg. Matured seabass can be induced 
to spawn by hormonal technique. 




Fig.8.31. Lates calcarifer 

The Central Institute of Brackish water Aquaculture (CIBA) 
has developed the hatchery technology for the first time in India. Sea bass 
can be cultured in saline and fresh water. They are cultured extensively in 
cages . Sea bass is also cultured in pond along with Tilapia in polycultre method. 

Metahaline culture 

Metahaline culture is practiced in areas where the water having the 
salinity range of 36-40 °/ ()() . Artemia salina , small crustaceans, popularly 
known as brine shrimp are cultured in this culture system. 




Fig.8.32. Artemia salina 

315 



They are the most popular live larval food currently used in the 
aquaculture industry.Artemia salina thrive well in salt lake and in salt pan. 

Aqua industry in India : 

In India aquaculture has been in progress for the past 5 decades. 
India's aquaculture industry is highly dependent on exports. World demand 
exceeds production and percapita consumption is also steadily increasing. 
Therefore India has great scope in expanding its aquaculture industry. There 
has been a remarkable improvement in the productivity level of aqua culture 
ponds from 600-800kg/ha/yr in 1960 to more than 2000 kg/ha/yr in the year 
2002. This proves the existing prospect of aquaculture. 

Government and Non-Government organisations : 

Government organisations such as Tamilnadu state fisheries (TNSF), 
TamilNadu Agricultural Universities(TNAU), Central Marine Fisheries 
Research Institute(CMFRI), Central Institute of Brackishwater 
Aquaculture(CIBA), Aquaculture Foundations in India(AFI), Central 
Institute of Freshwater Aquaculture (CIFA) have involved in extensive 
research activites. Marine Product Export Development Authority (MPEDA), 
an autonomous body is responsible for the development of the marine 
products industry with special reference to exports. 

Some of the non-governmental organisations and their role in 
aquaculture are as follows. 

Aquaculture Certification Council A. C.C : To certify standards of 
aquaculture facilities at the international level. 

International Coalition of Fisheries Association ICFA: In2001,ICFA 
made the ecoliability resolution supporting the idea of labeling in fisheries 
and aquaculture. 

Main environmental and public health concern: 

(i) The disease and parasites from farmed fish may spread to human 
population. 

316 



(ii) The chemicals used to treat farm fish diseases affect food chain. 

(iii) The organic fish waste and excess of nutrients can deteriorate the water 
quality. 

(iv) When mangroves are converted into aquaculture field, it causes erosion 
and flooding and thereby alter the natural drainage pattern. It also increases 
the salt intrusion. 

However the Food and Agricultural Organization (FAO) has made 
some progress in reducing the environment impact. It has made certain 
controls so that pollution is kept with in acceptable limit. The aquaculture 
since it yields good food supply it should be maintained without impairing 
environment by better recycling of nutrients and less wastage generation. 



317 



Self Evaluation (Sample Questions only) 

Unit - 1. Human physiology 
Part - 1 

Choose the correct answer : 

1. Intake of less amount of protein leads to the deficiency disease called 

a) Beri Beri b) Rickets c) Anaemia d) Kwashiorkar 

2. Each gram of lipid is capable of yielding. 

a) 9.3 calories b) 8.2 calories c) 7.1 calories d) 6 calories 

3. Deficiency of vitamin D causes 

a) Nyctalopia b) Xerophthalmia c) Osteomalacia d) Pellagra 

4. The calorie requirement for IRM at heavy work during occupational activites is 
a) 1100 calories b) 750 calories c) 2200 calories d) 460 calories 

5. The normal BMI (Body mass index) range for adults is 

a) 10- 15 b)12-24 c)15-20 d)19-25 

6. The normal blood glucose level during fasting is 

a) 70 to HOmg/dl b) 80 to 200 mg/dl c) 100 to 150mg/dl d) 200 to 250 mg/dl 

7. During emulsification, the bile salts convert bigger fat particles into smaller 
globules called 

a) granules b) oil c) chilomicrons d) millimicrons 

8. During root canal treatment, the cavity of the tooth is filled with a sealing paste 
made of 

a) chitin b) calcium carbonate c) iodised salt d) gutta-percha resin 

9. The gall stones are formed of 

a) calcium b) growing infected tissue c) cholesterol d) sodium crystals 

10. A fracture can be caused by 

a)shock b) loss of blood supply c) impact of force d) malnutrition 

11. The granulation of tissues around the site of fracture is called 
a) nodule b) papilla c) rudiment d) callus 



318 



12. An inflammation of synovial membrane is called as 

a) infective arthiritis b) osteoarthritis 

c) rheumatic arthiritis d) mechanical arthiritis 

13. During the contraction of muscle the ATP molecules bind with the active site of 

a) myosin filament b) myofibrils c) nerve endings d) actin filaments 

14. Ca ions necessary for the contraction of muscles are released from 

a) blood b) protoplasm c) synovial membrane d) sarcoplasmic reticulum 

15. What is the substance that destroys the muscle protein during rigor mortis 

a) proteolytic enzymes b) mitochondrial enzymes 

c) lysosome enzymes d) esterases 

16. The surface area of skin in our body is 

a)l.l-2.2m 2 b)2.2-3.3m 2 c) l-2m 2 d)0.5-1.5m 2 

17. An oily substance called sebum is secreted by 

a) sweat gland b) sebaceous gland c) thyroid gland d) tear gland 

18. Albinism is an extreme degree of generalized 

a) hyperpigmentation b) hypopigmentation 

c) failure of pigmentation d) perioral pigmentation 

19. Partial albinism causes 

a) leucoderma b) vitiligo c) melanoma d) dermatitis. 

20. Excessive exposure to U V-rays can cause 

a) vomitting b) redness of eyes c) colour change d) skin cancer 

21. Rag weed plant causes allergic responses and results in 

a) photo dermatitis b) herpetiformis dermatitis 

c) dermatitis artefacta d) all the above 

22. The amount of urea present in blood 

a) 0.02gms/100ml b)0.06gms/100ml 

c) 0.08gms/100ml d)0.01gms/100ml 

23. Urea biosynthesis takes place in 

a) blood b) liver c) cerebro-spinal fluid d) kidney 

24.Number of ATP molecules spent to convert ammonia to urea is 

a) four b) two c) three d) one 

319 



25. During glomerular filtration the malpighian body acts like a 

a) structural unit b) biological filter 

c) biological buffer d) acid-base balancer 

26. The amount of blood supplied to the kidneys is about 

a) 20-25% of cardiac output b) 25-30%of cardiac output 

c) 30-35% of cardiac output d) 35-40% of cardiac output 

27. Net filteration force which is responsible for the filtration in glomerulus is 

a)25mmHg b)50mmHg c)75mmHg d)80mmHg 

28. The amount of urea reabsorbed in the urinary tubules is 

a)5gm b) 17gm c)21gm d)20gm 

29. Area responsible for reabsorption of water, glucose, sodium phosphate and 
bicarbonates is 

a) glomerulus b) proximal convoluted tubules 

c) collecting duct d) descending limb of Henle's loop 

30. The volume of water found in the glomerular filterate is 

a) 170 lit b) 168.5 lit c) 165 lit d) 162.8 lit 

31. In recent days insulin resistant diabetes is commonly noticed in the age group 
of 

a)10-15years b)40-50years c) 35 -40 years d) 20-25years 

32. The type of diabetes that develops due to heavy viral infection belongs to the 
category called 

a) Insulin dependent diabetes b) non-insulin dependent diabetes 

c) inflammator diabetes d) harmful diabetes 

33. Which of the following is called artificial kidney? 

a) donar kidney b) dializer 

c) tissue-matched kidney d) preserved kidney 

Part - II 

1. Define carbohydrates and mention their compositions. 

2. Classify different types of monosaccharides ? 

3. What are polysaccharides ? Give examples. 

4. List out the essential aminoacids. 

5. What is kwashiorkar? Mention its symptoms. 

320 



6. State the functions of lipids? 

7. What is PUFA? Mention its significance 

8. Name different types of vitamins. 

9. Write down the expansions of IRM and IRW? and their characterestic features. 

10. What is obesity? 

11. Define BMI 

12. Write down the symptoms for hypoglycemia 

13. What are chilomicrons ? 

14. Name the substances used in treating the tooth decay 

15. What are the benefits of root-canal treatment 

16. What is peptic ulcer ? 

17. What is gall stone made up of ? 

18. State the main symptoms for appendicitis 

19. What is meant by hepatitis? 

20. Mention the reasons / causes for liver cirrhosis. 

21. What is meant by stress fracture ? 

22. Define the term physiotherapy. 

23. What does the term orthopedics refer to ? 

24. Name the fluids in the chambers of the eye. 

25. Name the parts involved in altering the curvature of the lens. 

26. What is short sightedness? 

27. How do you name the problems related to retina? 

28. Identify two reasons for cataract. 
28.WhatisCLR? 

30. What is nyctalopia? 

3 1 . What is a pink eye? 

32. What is Reissner's membrane? 

33. Which region of brain perceives sound? 

34. Give two reasons for loss of hearing. 

35. What is a bone conduction hearing aid. 

321 



36. Name the causes for noise pollution. 

37. Define permissive noise level. 

38. What happens during ventilation in the lungs? 

39. Name the muscles involved in respiration. 

40. Write down the composition of inhaled and exhaled air. 

4 1 . What is Herring - Breuer reflex? 

42. Name the microbes that cause pneumonia. 

43. What is pleurisy? 

44. What is pulse rate? 

45. Mention the reason for doing an angiogram. 

46. What is coronary angioplasty? 

47. What is done during Echo cardiography? 

48. What is arthrosclerosis? 

49. How can pulse rate be calculated ? 

50. Write down the importance of cardio pulmonary resuscitation. 

5 1 . Classify the lymphocytes of blood and mention their key function. 

52. What are called coagulation factors? 

53. Differentiate embolus from thrombus. 

54. What is menstrual cycle? 

55. What is corpus albicans? 

56. With whom does the technique of invitro fertilization adopted? 

Part -IH 

1. List out different types of carbohydrates and their significance? 

2. What are proteins ? Briefly explain. 

3. Why is water necessary for man ? 

4. Briefly explain the importance of minerals. 

5. Tabulate the calorie requirement of IRM and IRW being sedentary workers, moderate 
workers and heavy workers. 

6. What are the factors responsible for obesity? 

322 



7. Briefly explain the mode of digestion in duodenum. 

8. Write short notes on villi and their significance 

9. Write short notes on different types of Hernia 

10. Give an account of root-canal therapy. 

1 1 . Explain different types of bone fractures. 

12. Write short notes on the three phases in healing of bones in fracture. 

13. Explain the various factors attributed for bone joint dislocations. 

14. Describe the different types of arthiritis 

15. Describe the structure of sarcomere 

16. What are the benefits of aerobic exercise? 

17. Write down the various types of memory. 

18. "Sleep is a state of unconsciousness" - substantiate your statement. 

19. Write short notes on 'Stroke' 

20. Explain briefly the right and left brain concept. 

21. Describe the mechanism of reflex action 

22. Write a brief account on cerebro spinal fluid and its importance 

23. Define the terms transduction, transducer stimulus and response. 

24. What is accomodation of eye? 

25. Describe the photochemistry of retina. 

26. Differentiate myopia and hypermetropia. 

27. What is retinopathy? Comment on its types. 

28. Give an account of diagonosis and treatment of cataract. 

29. What is lens replacement? 

30. Write short notes on conjunctivitis. 

31. Suggest methods for eye care. 

32. Define sound and sound perception. 

33. Describe the role of middle ear in hearing . 

34. What are hearing aids? 

35. Write notes on the gustatory receptors. 

36. Explain the different processes involved in pulmonary respiration. 

323 



37. Write short notes on exchange of gases in alveoli. 

38. Comment on the sequences of events during the regulation of respiration. 

39. Explain briefly different types of bronchitis. 

40. Write short notes on cardiac cycle. 

41. Comment on the importance of ICCU. 

42. Describe briefly endocrine function of testes. 

43. Describe the process of ovulation and the fate of empty graffian follicle. 

44. Write short notes on in vitro fertilization 

Part -IV 

1 . Explain the digestive processes taking place in small intestine. 

2. Describe the mode of digestion of protein. 

3. Enumerate the steps involved in root canal treatment. 

4. Write an essay on any two disorders connected with the digestive system. 

5. Give an account on fracture and the healing method. 

6. Describe various types of arthiritis and their causes. 

7. Write an essay on muscle contraction. 

8. Write an essay on focussing mechanism in the human eye. 

9. Discuss the role of rods and cones in visual perception. 

10. Enumerate the various eye defects. Comment on corrective measures. 

1 1 . Describe the functional morphology of the organ of corti. 

12. Write an essay on hearing loss and the correcting measures adopted. 

13. Make a critical study of noise as an atmospheric pollutant. 

14. Describe the mechanism of breathing with proper illustration. 

15. Enumerate the events involved in the function of the human heart. 

16. Write an essay on composition of blood. 

17. Describe the various functions of the human male reproductive system. 

18. Write an essay on menstrual cycle. 

19. comment on various schemes suggested by the National Family Welfare Programmes 
and their importance. 



324 



Unit 2. Micro Biology 

Parti 
Choose the correct answer. 

1. Who first developed vaccine for rabies in man ? 

a) Robert koch b) Joseph Lister 

c) Louis Pasteur d) Stanley 

2. Which one of the following fields paved the sway for modern microbiology ? 

a) development of vaccines 

b) technique of new viral strains 

c) discovery of new viral strains 

d) development of pure culture technique 

3. Which one of the following statements is incorrect regarding the structure of 
viruses ? 

a) Nucleic materials are covered by a protein coat, called capsid. 

b) The capsid is made up of capsomeres 

c) Some animal viruses have an additional envelope 

d) The additional envelope is made up of glycoprotein 

4. Virions contain only a single copy of nucleic acid, hence they are called 

a) incomplete viruses b) haploid viruses 

c) ploidy viruses d) complete viruses 

5. Tumour inducing viruses are called 

a) Pathogenic viruses b) oncogenic viruses 

c) Para viruses d) variola viruses 

6. Which one of the following is a protozoan disease ? 

a) African sleeping sickness b) Measles 

c) Cholera d) Taeniasis 

7. Sexual reproduction of Plasmodium takes place in 

a) liver cells of man b)RBCsofman 

c) Plasma of man d) body of mosquito 

8. The pathogenic form of Entamoeba histolytica is 

a) encysted spores b) vegetative trophozoite 

c) merozoite d) schizont 

9. Which one of the following is a trematode worm ? 

a) Schistosomes b)Wuchereria 

c) Taenia d) Ascaris 

325 



10. The more promising chemotherapeutic agent for treating viral diseases is 

a) Tetracycline b) Ampicillin 

c) Interferon d) Anthramycin 

Part II 

1 . Define microbiology. 

2. Mention the use of pure culture technique ? 

3. What is meant by diploid cell strain ? 

4. Classify different types of malaria. 

5. What is amoebiasis ? 

6. What does the term 'Zooanthroponoses' refer to ? 

7. Listout notable antibiotics. 

8. Enumerate the methods of diagnosis of AIDS. 

9. Write the characteristics of species resistance. 

10. Define zoonoses. 

Part III 

1. Briefly describe the structure of virus. 

2. Write short notes on viral diseases in man. 

3. Give a brief account of life cycle of Schistostoma haematobium. 

4. Write an account on history of discovery and structure of HIV. 

5. Enumerate the adaptations of pathogenic microbes. 

6. Write the symptoms of AIDS, defined by WHO. 

7. Write a note on control and preventive measures of AIDS. 

Part IV 

1. Give an account on cultivation of animal viruses 

2. "Malaria-a major public health problem" - discuss. 

3. Write an essay on Pathogenicity of micro organisms and infections. 

326 



Unit 3. Immunology 
Parti 

Choose the correct answer 

1. Which of the following can induce immunity 

a) bacteria b) viruses 

c) parasites d) all the above 

2. Skin is a/an 

a) anatomical barrier b) physiological barrier 

c) phagocytic barrier d) inflammatory barrier 

3. Which among the following is anti-bacterial ? 

a) interferon b) lysozyme 

c) hormone d) protein 

4. Which of the following is anti-viral 

a) lysozyme b) interferon 

c) protein d) hormone 

5. Identity the phagocytic cells from the following combinations 

a) Macrophage and neutrophil b) Lymphocyte and eosinophil 

c) Macrophage and eosinophil d) Eosinophil and neutrophil 

6. Histamine is secreted by 

a) Epithelial cell b) Mast cells 

c) Red blood cells d) white blood cells 

7. Humoral immunity consists of 

a) normal cells b) pathological cells 

c) cytotoxic cells d) immunoglobulin molecules 

8. Which type of graft is used in plastic surgery ? 

a) xenograft b) allograft 

c) autograft d) isograft 

9. MHC genes in mouse is located in 

a) Chromosome 1 b) Chromosome 2 

c) Chromosome 4 d) Chromosome 6 

10. Which of the following is an auto immune disease ? 

a) AIDS b) Multiple sclerosis 

c) Cancer d) Asthma 

11. Which antibody characterizes the allergic reaction 

a)IGG b)IGA 

c) IGM d) IGE 



327 



12.SCIDisdueto 

a) Adenosine deaminase deficiency b) Glucose oxidase deficiency 

c) Phosphatase deficiency d) Lactate dehydrogenase deficiency 

13. Which of the following causes AIDS ? 

a) Bacteria b) Fungus 

c) Retro virus d) TMV 

14. Thymus growth occurs up to 

a) 17 years b) 12 years 

c) 5 years d) 30 years 

15. Which of the following secretes immunoglobulin 

a) T-lymphocyte b) B-lymphocyte 

c) Macrophage d) Mast cells 

16. The H-chain of immunoglobulin has a molecular weight 

a) equivalent to that of light chain 

b) Twice that of light chain 

c) Triple the amount of light chain 

d) Twice as that of dark chain 

17. Immunoglobulins are chemically 

a) glycogens b) glyco-proteins 

c) glycolipids d) Lipo-proteins 

18. Hyper variability regions are present in 

a) heavy chain only b) light chain only 

c) heavy and light d) dark chain 

19. Organ transplantation from pig to human is an example for 

a) Autograft b) Allo-graft 

c) ISO-graft d) Xeno-graft 

20. Graft between identical twins is called 

a) Xeno-graft b) Allograft 

c) Auto graft d) Iso graft 

Part -II. 

1. What is Immunology ? 

2. What are the four types of infectious agents ? 

3. Define innate immunity 

4. What is lysozyme ? 

5. What is phagocytosis ? 

6. What is acquried immunity ? 

7. Differentiate cell mediated and humoral immunity. 

328 



8. Differentiate active and passive adapted immunity. 

9. What are the immunoglobins ? 

10. What are the three main functions of antibodies ? 

11. State the functions of spleen. 

12. What is an immunogen ? 

13. Define the term 'antigen' ? 

14. What are haptens ? 

15. Distinguish paratope and epitope. 

16. Name the five classes of immunoglobins. 

17. Distinguish the variable and constant region in the IG molecule. 

18. Distinguish autograft and allograft. 

19. How does Xenograft differ from Isograft ? 

20. What are immuno suppressant drugs ? 

Part -III 

1. What are the specific features of adaptive immunity and specific immunity ? 

2. Draw a labelled sketch of the structure of immunoglobulin. 

3. Give an account of the structure and functions of immunoglobulin. 

4. Briefly describe the genetic basis of tissue transplantation. 

5. What are the symptoms of graft rejection ? 

6. Give an account of immuno deficiency diseases. 

7. Describe Bursa of Fabricius ? 

8. What are the anatomical and physiological barriers in first line defence ? 

Part - IV 

1. Write an essay on lymphoidal organs and their functions. 

2. Critically evaluate the transplantation immunology. 

3. Write an essay on natural innate immunity 

4. Give an account of the mechanisms of acquired immunity. 

Unit 4. Modern Genetics 

Parti 

Choose the correct answer. 

1. In which prokaryote has voluminous genetical works been made 

a) TMV virus b) Phage 

c) Escherichia coli d) coliform bacteria 



329 



2. Who discovered the double helix DNA model ? 

a) G.H. Khorana b) Mendel 

c) T.H.Morgan d) Watson and Crick 

3. About how many hereditary diseases in human beings had been identified ? 

a) more than 300 b) less than 300 

c) about 400 d) about 100 

4. To obtain information about genetic characters in man which of the following 
helps? 

a) Biochemical test b) Hybridization 

c) Pedigree analysis d) Inbreeding 

5. Sickle cell anaemia is due to 

a) autosomal gene b) sex chromosomal gene 

c) vitamin deficiency d) hormone imbalance 

6. Albinism is due to 

a) absence of melanin b) absence of vitamins 

c) presence of melanin d) absence of hormone 

7. Name the human disease due autosomal dominant gene 

a) sickle cell anaemia b) thalasemia 

c) SCID d) huntington's chorea 

8. Idiogram means 

a) Diagrammatic representation of genes 

b) Diagrammatic representation of chromosome 

c) Graph showing heart defect 

d) electro cardiogram 

9. In human chromosome karyotyping the chromosomes 4 and 5 belong to group 

a) A b) B 

c) C d) D 

10. What is the name for mobile genetic elements 

a) plasmids b) pili 

c) barr body d) transposons 

Part II 

1. What is pedigree analysis ? 

2. What are the clinical manifestations of thalassemia ? 

3. Mention any two uses of karyotyping 

4. What is foreign DNA in genetic engineering ? 



330 



5. What are cloning vectors ? 

6. Name the bacterial species employed in genetic engineering. 

7. What is called DNA segmenting ? 

8. What is called differentiation ? 

9. What is gene therapy? Name the two types of gene therapy. 

10. What is a data base in bioinformatics ? 

Part IH 

1 . Give an account of albinism and SCID. 

2. What are the seven groups in human chromosome karyotyping? Mention their 
respective schromosomes ? 

3. What are the uses of recombinant DNA technology. 

4. Mentions the ethical problems of cloning. 

Part IV 

1. Write an essay on DNA recombinant technology 

2. Illustrate with example the cloning mechanism. 

3. Give an account of human genome project. 

4. Write an essay on bioinformatics. 

5. Write an essay on protein structure and protein model and its uses. 

Unit 5. Environmental Science 

Parti 
Choose the correct answer 

1. What is the rate of growth of human population ? 

a) 10 billion per year b) 90 billion per year 

c) 1 billion per year d) 80 billion per year 

2. The present sudden acceleration of population is called as 

a) population explosion b) population bomb 

c) population trap d) all the above 

3. Global warming is caused due to 

a) lack of rainfall b) presence of a hole in ozone layer 

c) human activities against nature d) extinction of animals and plants 

4. The most abundant green house gas is 

a) N0 2 b) C0 2 

c) 3 d) S0 2 



331 



5. Which of the following gas destroys ozone layer faster ? 

a) chloroflurocarbons b) hydrochlorofluro carbons 

c) both (a) and (b) d) sulphur dioxide 

6. Which is a better method to dispose large amounts of water carrying relatively 
small amounts of chemical wastes? 

a) land filling method b) Deep-well injection 

c) Surface impoundments d) incineration 

7. Which one of the following organisms plays vital role in pollination of trees in 
tropical forest? 

a) mimic moths b) orchid bees 

c) Rhinocerous beetles d) Humming birds 

8. Which is commonly considered as a biologists paradise? 

a) Gulf of Mannar Biosphere Reserve b) Nilgiri Biosphere Reserve 

c)NandaDevi d) Great Nicobar 

9. The amount of energy the earth receives from the sun, per year is 

a) 1000 K calories b) 10 X 10 3 ° K calories 

c) 5 X 1 20 K calories d) 1 5 X 1 25 K calories 

10. Which is considered as a future source of power, that can meet our unlimited 
demand ? 

a) Hydel power b) Hydrogen 

c) Thermal power d) Solar power 

11. Of the total amount of water, how much is available as fresh water? 

a) 10% b)3% c)15% d)50% 

12. Which of the following countries depend on desalination process for getting 
fresh water? 

a) Dubai b) Oman c) Bahrain d) all the above 

Part II 

1. Define ecology. 

2. How does population growth differ from food production? 

3. What is known as global warming? 

4. What are the effects of ozone depletion? 

5. How is the sewage water treated by primary treatment method? 

6. What is bio-diversity? 

7. Write the characteristics of a bioreserve. 

8. List out the names of bioreserves of India. 

332 



9. What is known as geothermal energy? 

10. What are the advantages of solar energy? 

11. What is known as relative poverty? 

12. What is meant by seeding of clouds? 

Part IH 

1. Write short notes on growing population and its impact on enviroment. 

2. List out the effects of global warming. 

3. "Ozone is a natural sun block" - Discuss. 

4. Write about the various types of wastes. 

5. Write short notes on waste water treatment and management. 

6. Briefly describe the reasons for decline of biodiversity. 

7. Write an account of fresh water resources. 

Part IV 

1. Write an essay on green house gases and their impact on the environment. 

2. How will you manage hazardous wastes? Discuss it with current knowledge. 

3. What is known as energy crisis? what are the steps to be taken to solve energy 
crisis? 

4. Give an account on poverty? 

5. "Conservation of freshwater" - sDiscuss. 

Unit 6. Applied Biology 

Parti 

Choose the correct answer 

1. The breeds of cattle now available in India are 

a) 29 b) 30 

c) 26 d) 20 

2. Which one of the following is not a draught breed? 

a) Kangayam b) Khillar 

c) Kankrej d) Hallikar 

3. The other name for the cattle sindhi is 

a) Kongu b) Nellore 

c) Red karachi d) Decan 

4. Kangayam originated from 

a) Punjab b) Coimbatore 

c) Karnataka d) Kathiawar 



333 



5. Which of the following is not an exotic breed? 

a) Jersey b) Gir 

c) Brown swiss d) Ayreshire 

6. Which one of the following is a contagious disease of the cattle? 

a) constipation b) milk fever 

c) cow pox d) diabetes 

7. Feeding jaggery along with lime water is one of the first aid measure for 



a) Diarrhoea 
c) milk-fever 



b) constipation 
d) anthrax 



c) Eurpoean bee 
c) Worker 



d) Rock bee 



8. Mating of closely related animals is called 

a) outbreeding b) artificial insemination 

c) cross breeding d) Inbreeding 

9. The milk which the following cow is characterised by high carotene content? 

sa)Sindhi b) Haryana 

c) Gir d) Jersy 

10. For anthrax one of the following symptom can be seen 

a) swelling of udder b) blood discharge from natural openings 

c) loss of appetite d) lack of chewing 

11. Apisindicais 

a) India bee b) .African bee 

12. Bee milk is produced by 
a) Drones b) Queen 

13. Sterile females are 
a) Queen b) Worker 

14. Stingless bees are 
a) Queen b) Drone 

15. Modern bee hive consists of 

a) 5 Compartments b) 4 Compartments c) 6 Compartments d) 7Compartments 

16. Fquipment used for spinning the comb is 

a) Beeveil b) Bee brush c) Honey extractor d) Bee gloves 

17. The resin is the component of 

a) Bee venom b) Bee bread c) Bee glue d) Bee milk 

18. The disease Nosema apis is caused by 

a) Bacteria b) Protozoa c) Fungus d) Virus 



c) Drone 
c) Worker 



d) An adult bee 

d) Both Queen and Worker 

d) Both Drone and Worker 



334 



19. Bee bread is a mixture of 

a) Nectar and water b) Nectar and pollen 

c) Pollen and royal jelly d) Propolis and royal jelly. 

20. One of the bee hive product used for apitherapy 

a) Propolis b) Royal jelly c) Bee venom d) Pollen 

Part II 

1. What is meant by dairy operations? 

2. How are catties classified ? 

3. Compare the udder of Sindhi with kangayam. 

4. How are dual purpose breeds helpful for mankind. 

5. Write down the origin and distribution of the cattle kangayam. 

6. How will you identify a healthy cattle? 

7. Mention the bacterial disease of cattle and its symptoms. 

8. What are the control measures of cow pox? 

9. What is the first aid given to cattle for constipation? 

10. List out the different types of diseases of cattle. 

11. Define draught breeds. 

12. What are the advantages of artificial insemination? 

13. What is artificial insemination? 

14. Define outbreeding. 

15. Define cross breeding. 

16. Compare the bullocks of Sindhi, Ongole and Kangayam. 

17. Define breed. 

18. Define Sericulture. 

19. Name the types of silk. 

20. What is fibroin? 

335 



21. What is sericin 

22. What are the three stages of sericulture ? 

23. What is the function of salivary gland of silk worm? 

24. What is cocoon? 

25. What is instar? 

26. What is imago ? 

27. What is spinneret? 

Part IH 

1. Describe a dual purpose breed. 

2. What is meant by exotic breeds? compare the lactational capacity of this breed 
with milch breed? 

3. How does contagious disease differ form non contagious disease. Describe any 
one of the non contagious diseases of cattle in detail? 

4. What is the importance of dairy technolgy? 

5. Write short notes on artificial insemination. 

Part IV 

1. Give an account on dairy breeds. 

2. Write an essay on common diseases of cattle. 

3. Discuss the various techniques adopted in cattle breeding. 

Unit 7. Theories of Evolution 
Parti 

Choose the correct answer 

1. The book 'Philosophic Zoologique' was published by 

a) Charles Darwin b) August Weismann 

c) Mc Dougall d) Jean Baptiste de Lamarck 

2. The German scientist who segregated germplasm from somatoplasm for the 
first time was 

a) Lamarck b) Malthus 

c) Weismann d) Hugo de vries 

336 



3. Mc Dougall supported neo-lamarckism and proved the concept of 

a) Direct action of environment on organism 

b) Learning is an acquired character 

c) Speed of learning increased from generation to generation 

d) All the above 

4. Darwin supported the following concepts for evolution 

a) arrival of the fittest 

b) survival of the fittest 

c) The differentiation of somatoplasm germplasm 

d) genetic recombinations 

5. The book "Process of organic evolution" to support modern synthetic theory of 
evolution was provided by 

a) Dobzhansky b) Stebbins 

c) Hardy-weinberg d) Hugo de vries 

6. The factor that enriches the genepool with new modified genes 

a) mutation b) somatic variation 

c) decrease in chromosomes d) increase in cytoplasm 

Part II 

1 . State the theory of Lamarck. 

2. Define the law of use and disuse. 

3. Quote the facts of neo-lamarckism. 

4. Define the germ plasm theory. 

5. State the view of McDougall. 

6.. What is meant by "survival of the fittest"? 

7. Mention any two objections to Darwinism. 

8. Mention the significance of neo- Darwinism. 

9. State the modern synthetic theory. 

10. What is meant by "gene pool"? 

1 1 . Name two books that explain the basic concepts of evolution. 
12.What is meant by chromosomal aberration? 

13. State the law of genetic drift. 

14. What is a species? 

15. Define founder principle. 



337 



Part IH 

1 . Write short notes on neo-Lamarckism. 

2. Describe the modern concept of Natural selection. 

3. Write down the mechanism that prevents inter specific crosses. 

4. Briefly describe Sewal Wright effect. 

5. Give an account of different types of species. 

Part IV 

1 . Enumerate the principle of Lamarckism in support of evolution. 

2. What are the conditions under which Hardy-Weinberg law operates? 

3. Write an essay on theory of Natural selection. 

Unit - 8 Aquaculture 
PART - 1 

1. The fish cultured in fresh water is 

a. rohu b. mugil c lobster d. milk fish 

2. In fresh water aquaculture the salinity of the fresh water should be 
a.>0.50°/ 00 b.>0.55"/ 00 c.<0.50°/ 00 d.<0.55°/ 00 

3. In metahaline aquaculture the salinity range will be 

a. 30-40° / 00 b. 36-42° / 00 c. 30-40° / 00 d.35-40°/ 00 

4. Which one of the following is an exotic fish. 

a. catla b. rohu c. tilapia d. mugil 

5. Which one of the following culture practice takes place in cold water. 
a. ornamental fish culture b. race way culture 

c. sport fish culture d. larvivorous fish culture 

6. The size of fry is 

a. < 2.0cm b. < 2.2cm c. <2.5cm d. <2.7 cm 

7. The possible temperature range for survival of different fishes is 
a. 14-15 °C b. 10-37 °C c.5-9°C d. 10-15°C 

8. The usual size of fish cultured in nursery pond is 
a. less than 2.5 cm. b. more than 1.5 cm. 
c. less than lcm d. more than 4 cm 

9. The maximum permissible density of hatchlings is 

a. 10.5 million /ha b. 10 million/ha c. 10 billion /ha d. lmillion/ha 

10. The Indian major carp can survive in a temperature range of 
a. 14-15°c b.5-9°c c. 13-14°c d. 16-25° 

338 



11. Ideal pH range for pond water is 

a. 6.5-9 b. 3.5-4.5 c. 4.5-5.5 d. 5.5-6.5 

12. The suitable hardness for pond water is 

a. 17ppm b. 14ppm c. 13ppm d. 12ppm 

13. Macrobrachium rosenbergii can be identified by the presence of 

a. 1-7 horizontal lines on the carapaca b. 1-6 horizontal lines on the carapaca 
c. 1-8 horizontal lines on the carapaca d. 1-9 horizontal lines on the carapaca 

14. In the absence of natural food, which of the following organism become cannibals. 

a. Penaeus indicus b. Scylla serrata 

c. Catla-catla d. Macrobrachium rosenbergii 

15. The preparation of pituitary extract is done by 

a. Homogeniser b. Distillation c. Hypophysation d. Dehydration 

16. The preferable age group for the selection of breeder in hypophystation 
technique is 

a. 4-5 years b. 5-6 years c. 2-4 years d. 1-2 years. 

17. The quantity of second dose of pituitary extract lies in the range of 

a. 5-8 mg/kg b. 3-4mg/kg c.2-3mg/kg d. 2-5 mg/kg 

18. Blindness and haemorrhage are the symptoms for 

a. Costiasis b. Dropsy c. Gillrot d. Saprolegniasis 

19. The aerator in the aquariam keeps the water 

a. Warm b. Oxgenated c. free from turbidity d. free form ammonia 

20. The salinity range 3%e to 29%c may prevail in the culture of 

a. mugil b. mussels c. artemia salina d. milk fish 

Part II 

1. What is Aquaculture? 

2. What are the major types of Aquaculture methods? 

3. Define mariculture? 

4. Distinguish between fresh water & marine water? 

5. Define integrated fish culture? 

6. Name the culturable organisms of freshwater aquaculture? 

7. What are bunds? 

8. What are the components of a typical pond? 

9. What is the structure of a nursery pond and its nature of utilisation? 

10. What are the physical & chemical factors of culturable pond? 

339 



1 1 . Name 4 species of freshwater culturable organisms. 

12. What is hypophystation? 

13. What is called Hapa? 

14. What is spawning? 

15. What is dropsy? 

16. What is costiasis? 

17. What is gill-rot? 

18. What is called spat? 

19. What are called bouchots? 

20. Name the cultivable species of edibe oyster & pearl oyster. 

21. Name cultivable species of marine Aquaculture? 

22. Name cultivable species of freshwater Aquaculture? 

23. What are called pens? 

24. Define mata-haline culture 

25. Expand the following acronym. 

(a) CMFRI (b) MPEDA (c) CIB A (d) ICFA 

Part III 

1. What is freshwater Aquaculture? and classify its types 

2. Give an account of integrated fish culture? 

3. Explain composit fishculture. 

4. Give an account of bunds. 

5. What are the characteristic features of location of a pond? 

6. Explain the physio-chemical factors of a pond. 

7. Give an account of bionomics of Catla-catla 

8. Give an account of bionomics of Rohu. 

9. Give an account of bionomics of the Tilapia mosambica. 

10. What are the bionimics of freshwater prawn? 

11. What are the salient features of Macrobrachium rosenbergii. 

12. Give an account of fish diseases. 

13. How do we setup an aquarium tank? 

340